JP2016110980A - Light-emitting element, light-emitting device, electronic equipment, and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a light-emitting efficiency of a light-emitting element.SOLUTION: A light-emitting element has an EL layer sandwiched by a pair of electrodes. The EL layer includes a first light-emitting layer and a second light-emitting layer. The first light-emitting layer includes a luminescence material and a host material. The second light-emitting layer includes: a phosphorescent material; a first organic compound; and a second organic compound. A light-emitting spectrum from the second light-emitting layer includes a peak in a yellow wavelength region, and the first organic compound and the second organic compound form an excited complex.SELECTED DRAWING: Figure 1

Description

  One embodiment of the present invention relates to a light-emitting element in which a light-emitting layer that can emit light by applying an electric field is sandwiched between a pair of electrodes, or a light-emitting device, an electronic device, and a lighting device each having the light-emitting element.

  Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Alternatively, one embodiment of the present invention relates to a process, a machine, a manufacture, or a composition (composition of matter). Therefore, the technical field of one embodiment of the present invention disclosed in this specification more specifically includes a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, a driving method thereof, Alternatively, the production method thereof can be given as an example.

  In recent years, research and development of light-emitting elements (organic EL elements) using electroluminescence (EL) using organic compounds have been actively conducted. The basic structure of these light-emitting elements is such that an organic compound layer (EL layer) containing a light-emitting substance is sandwiched between a pair of electrodes. By applying a voltage to this element, light emission from the light-emitting substance can be obtained.

  A light-emitting element in which a layer containing an organic compound is provided between a pair of electrodes and a light-emitting device including the light-emitting element are referred to as an organic electroluminescent element and an organic electroluminescent device, respectively. The organic electroluminescent device can be applied to a display device, a lighting device, and the like (for example, see Patent Document 1).

JP 2012-186461 A

  One of the problems of one embodiment of the present invention is to improve the light emission efficiency of a light emitting element. Another object of one embodiment of the present invention is to provide a novel semiconductor device, a novel light-emitting element, or a novel light-emitting device. Note that the description of these problems does not disturb the existence of other problems. Note that one embodiment of the present invention does not necessarily have to solve all of these problems. Issues other than these will be apparent from the description of the specification, drawings, claims, etc., and other issues can be extracted from the descriptions of the specification, drawings, claims, etc. It is.

  One embodiment of the present invention is a light-emitting element in which an EL layer is sandwiched between a pair of electrodes. The EL layer includes a first light-emitting layer and a second light-emitting layer. The layer includes a fluorescent material and a host material, and the second light-emitting layer includes a phosphorescent material, a first organic compound, and a second organic compound, and the second light-emitting layer includes: The emission spectrum of the light-emitting element has a peak in a yellow wavelength region, and the first organic compound and the second organic compound form an exciplex.

  In the above structure, the second light-emitting layer preferably has one phosphorescent material.

  In each of the above structures, it is preferable that energy be transferred from the exciplex to the phosphorescent material.

  In each of the above structures, the singlet excitation level of the host material is larger than the singlet excitation level of the fluorescent material, and the triplet excitation level of the host material is smaller than the triplet excitation level of the fluorescent material. And preferred.

  In each of the above structures, the triplet excitation level of the host material is preferably smaller than the triplet excitation level of the first organic compound and the second organic compound.

  In each of the above structures, it is preferable that the first light-emitting layer and the second light-emitting layer have regions in contact with each other.

  In each of the above structures, it is preferable that the first light-emitting layer and the second light-emitting layer have regions separated from each other. In the case where the first light-emitting layer and the second light-emitting layer have regions that are separated from each other, a hole-transporting material and an electron-transporting material are interposed between the first light-emitting layer and the second light-emitting layer. It is preferred to have a mixed layer.

  In each of the above structures, the second light-emitting layer is preferably provided over the first light-emitting layer.

  Another embodiment of the present invention is a light-emitting device including the light-emitting element having any of the above structures and a transistor or a substrate.

  Note that the light-emitting device in this specification and the like includes an image display device using a light-emitting element. In addition, a connector, for example, a module with an FPC (Flexible Printed Circuit) attached to the light emitting element, a module with an anisotropic conductive film or TCP (Tape Carrier Package) attached, and a module with a printed wiring board at the end of the TCP Alternatively, a module in which an IC (integrated circuit) is directly mounted on a light emitting element by a COG (Chip On Glass) method may include a light emitting device.

  Another embodiment of the present invention is an electronic device including the light-emitting device having the above structure and an external connection port, a keyboard, operation buttons, a speaker, or a microphone. Another embodiment of the present invention is an electronic device including the module having the above structure and an external connection port, a keyboard, operation buttons, a speaker, or a microphone. Another embodiment of the present invention is a lighting device including the light-emitting device having the above structure and a housing.

  According to one embodiment of the present invention, the light emission efficiency of the light emitting element can be improved. Alternatively, according to one embodiment of the present invention, a novel semiconductor device, a novel light-emitting element, or a novel light-emitting device can be provided.

  Note that the description of these effects does not disturb the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. It should be noted that the effects other than these are naturally obvious from the description of the specification, drawings, claims, etc., and it is possible to extract the other effects from the descriptions of the specification, drawings, claims, etc. It is.

FIG. 6 is a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention. The figure explaining the correlation of the energy level in a light emitting layer. The figure explaining the correlation of the energy level in a light emitting layer. FIG. 6 is a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention. FIG. 6 is a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention. 4A and 4B are a top view and cross-sectional views illustrating a light-emitting device of one embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a light-emitting device of one embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a light-emitting device of one embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a light-emitting device of one embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a light-emitting device of one embodiment of the present invention. 4A and 4B are a block diagram and a circuit diagram illustrating a display device of one embodiment of the present invention. The perspective view explaining a display module. 6A and 6B illustrate electronic devices. The figure explaining an illuminating device. FIG. 6 is a schematic cross-sectional view illustrating an element structure of a light-emitting element of Example 1 to Example 3. 3A and 3B illustrate current density-luminance characteristics and voltage-luminance characteristics of the light-emitting element of Example 1. FIG. 4A and 4B illustrate luminance-power efficiency characteristics and luminance-current efficiency characteristics of the light-emitting element of Example 1. FIG. FIG. 6 illustrates an emission spectrum of the light-emitting element of Example 1. 6A and 6B illustrate current density-luminance characteristics and voltage-luminance characteristics of the light-emitting element of Example 2. FIG. 6A and 6B illustrate luminance-power efficiency characteristics and luminance-current efficiency characteristics of the light-emitting element of Example 2. FIG. FIG. 9 illustrates an emission spectrum of the light-emitting element of Example 2. 6A and 6B illustrate current density-luminance characteristics and voltage-luminance characteristics of the light-emitting element of Example 3. FIG. 6A and 6B illustrate luminance-power efficiency characteristics and luminance-current efficiency characteristics of the light-emitting element of Example 3. FIG. FIG. 6 illustrates an emission spectrum of the light-emitting element of Example 3. 6 is a schematic cross-sectional view illustrating an element structure of a light-emitting element of Example 4. FIG. 6A and 6B illustrate current density-luminance characteristics and voltage-luminance characteristics of the light-emitting element of Example 4. FIG. FIG. 6 illustrates an emission spectrum of the light-emitting element of Example 4. FIG. 10 is a graph for explaining luminance-external quantum efficiency characteristics of the light-emitting element 11 of Example 5. FIG. 6 illustrates an emission spectrum of the light-emitting element 11 of Example 5. 6A and 6B illustrate reliability of the light-emitting element 11 according to Example 5. FIG. 10 is a graph for explaining luminance-external quantum efficiency characteristics of the light-emitting element 12 of Example 5. FIG. 10 illustrates an emission spectrum of the light-emitting element 12 of Example 5. 6A and 6B illustrate reliability of the light-emitting element 12 according to Example 5.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that one embodiment of the present invention is not limited to the following description, and various changes can be made in form and details without departing from the spirit and scope of the present invention. Therefore, one embodiment of the present invention is not construed as being limited to the description of the following embodiment modes.

  Note that the position, size, range, and the like of each component illustrated in the drawings and the like may not represent the actual position, size, range, or the like for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in the drawings and the like.

  In this specification and the like, the ordinal numbers attached as the first, second, etc. are used for convenience and do not indicate the order of steps or the order of lamination. Therefore, for example, the description can be made by appropriately replacing “first” with “second” or “third”. In addition, the ordinal numbers described in this specification and the like may not match the ordinal numbers used to specify one embodiment of the present invention.

  Further, in this specification and the like, in describing the structure of the invention with reference to the drawings, the same reference numerals are used in different drawings.

  In this specification and the like, the terms “film” and “layer” can be interchanged with each other depending on the case or circumstances. For example, the term “conductive layer” may be changed to the term “conductive film”. Alternatively, for example, the term “insulating film” may be changed to the term “insulating layer” in some cases.

In this specification and the like, a fluorescent material is a material that emits light in the visible light region when relaxing from the lowest singlet excited state (S ₁ level) to the ground state. A phosphorescent material is a material that emits light in the visible light region at room temperature when relaxing from the lowest level (T ₁ level) of a triplet excited state to the ground state. In other words, a phosphorescent material is a material that can convert triplet excitation energy into visible light.

  In this specification and the like, blue light has at least one emission spectrum peak in a blue wavelength region of 420 nm or more and 480 nm or less, and green light is at least one in a green wavelength region of 500 nm or more and less than 550 nm. The yellow light has at least one emission spectrum peak in the yellow wavelength region of 550 nm to 590 nm and the red light has at least one in the red wavelength region of 600 nm to 740 nm. It has two emission spectral peaks.

(Embodiment 1)
A light-emitting element of one embodiment of the present invention is described below with reference to FIGS. 1A is a schematic cross-sectional view of the light-emitting element 100 of one embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view of the light-emitting element 140 of one embodiment of the present invention.

  A light-emitting element 100 illustrated in FIG. 1A has a structure in which an EL layer 130 is sandwiched between a pair of electrodes (a first electrode 101 and a second electrode 102). In addition, the EL layer 130 includes a first light-emitting layer 113 and a second light-emitting layer 114. In the light-emitting element 100, the hole injection layer 111, the hole transport layer 112, the electron transport layer 115, and the electron injection layer 116 are illustrated as the EL layer 130, but the stacked structure thereof is an example. The structure of the EL layer 130 in the light-emitting element of one embodiment of the present invention is not limited thereto. Note that in the light-emitting element 100, the first electrode 101 functions as an anode and the second electrode 102 functions as a cathode.

  The first light-emitting layer 113 includes a fluorescent material and a host material. The emission spectrum from the first light-emitting layer 113 preferably has a peak in the blue wavelength region. The second light-emitting layer 114 includes a phosphorescent material, a first organic compound, and a second organic compound. The emission spectrum from the second light-emitting layer 114 preferably has a peak in the yellow wavelength region. The second light-emitting layer 114 preferably has one phosphorescent material. The first organic compound and the second organic compound form an exciplex (also referred to as an exciplex). One of the first organic compound and the second organic compound functions as a host material of the second light-emitting layer 114, and the other of the first organic compound and the second organic compound is the second light-emitting layer 114. Functions as an assist material. In the following description, the first organic compound is used as a host material and the second organic compound is used as an assist material.

  The first light-emitting layer 113 and the second light-emitting layer 114 have the above-described structure, whereby the light emission of the fluorescent material from the first light-emitting layer 113 (here, light emission having a peak in the blue wavelength region), the first The light emission of the phosphorescent material from the second light-emitting layer 114 (here, light emission having a peak in the yellow wavelength region) can be efficiently obtained.

In addition, it is preferable that the T ₁ level of the host material of the first light-emitting layer 113 be smaller than the T ₁ level of the _first organic compound and the second organic compound included in the second light-emitting layer 114. In the first light emitting layer 113, S ₁ level of the host material is greater than S ₁ level of fluorescent material, and, when the T ₁ level of the host material is smaller than the T ₁ level of the fluorescent material preferable.

  The combination of the first organic compound and the second organic compound that form the exciplex in the second light-emitting layer 114 may be a combination that can form an exciplex, but one of them has hole transportability. More preferably, the other material is a material having an electron transporting property. In this case, it becomes easy to form a donor-acceptor type excited state, and an excited complex can be formed efficiently. Further, when a combination of the first organic compound and the second organic compound is configured by a combination of a material having a hole transporting property and a material having an electron transporting property, the carrier balance is easily controlled by the mixing ratio. be able to. Specifically, a material having a hole transporting property: a material having an electron transporting property = 1: 9 to 9: 1 (weight ratio) is preferable. In addition, since the light-emitting element 100 having the above structure can easily control the carrier balance, the recombination region can be easily controlled.

  In the light-emitting element 100, the carrier recombination region is preferably formed with a certain distribution. Therefore, it is preferable that the first light-emitting layer 113 or the second light-emitting layer 114 have an appropriate carrier trapping property, and in particular, the phosphorescent material included in the second light-emitting layer 114 has an electron trapping property. It is preferable.

  Note that the light-emitting element 100 preferably has a structure in which light emission from the first light-emitting layer 113 has a light emission peak on a shorter wavelength side than light emission from the second light-emitting layer 114. A light-emitting element using a phosphorescent material that emits light having a short wavelength tends to deteriorate in luminance. Therefore, a light-emitting element with small luminance deterioration can be provided by using short-wavelength light emission as fluorescent light emission.

  In the light-emitting element 100, since the first light-emitting layer 113 and the second light-emitting layer 114 are stacked in contact with each other, the number of layers for forming the EL layer 130 is small and productivity is high.

  In addition, the light-emitting element 100 can be a multicolor light-emitting element by obtaining light with different emission wavelengths in the first light-emitting layer 113 and the second light-emitting layer 114. Since the light emission spectrum of the light emitting element 100 is light in which light emission having different light emission peaks is synthesized, it becomes a light emission spectrum having at least two maximum values.

  The light emitting element 100 is also suitable for obtaining white light emission. White light emission can be obtained by making the light of the first light-emitting layer 113 and the second light-emitting layer 114 have complementary colors.

  In addition, by using a plurality of light-emitting substances having different emission wavelengths for the first light-emitting layer 113, white light emission with high color rendering properties composed of three primary colors or four or more emission colors can be obtained. In this case, the first light-emitting layer 113 may be further divided into layers, and a different light-emitting material may be included for each of the divided layers.

<Light emitting mechanism of second light emitting layer>
Here, FIG. 2A shows the correlation of energy levels among the first organic compound, the second organic compound, and the phosphorescent material in the second light-emitting layer 114. In addition, the notation and code | symbol in FIG. 2 (A) are as follows.
Host: first organic compound Assist: second organic compound Guest: phosphorescent material _SPH : lowest level of singlet excited state of host material (first organic compound) _TPH : host material the lowest level · T _PG triplet excited state (first organic _compound): guest material (phosphorescent material) of the lowest level · S _E triplet excited _states: most of the singlet excited state of the exciplex Low level, T _E : lowest level of triplet excited state of exciplex

In the light-emitting element 100 of one embodiment of the present invention, the first organic compound and the second organic compound included in the second light-emitting layer 114 form an exciplex. The lowest level (S _E ) of the singlet excited state of the exciplex and the lowest level (T _E ) of the triplet excited state of the exciplex are adjacent to each other (see FIG. 2 (A) Route A). .

An exciplex is an excited state composed of two kinds of substances, and in the case of photoexcitation, one molecule in an excited state takes in another substance in the ground state. And if it will be in a ground state by emitting light, the two types of substances that have formed the exciplex will also behave as separate original substances. In the case of electrical excitation, an exciplex can be formed by the proximity of one cation molecule (hole) and the other anion molecule (electron). That is, in electrical excitation, an exciplex can be formed without forming an excited state in any molecule, leading to a reduction in driving voltage. Then, the energy of both the (S _E ) and (T _E ) of the exciplex is transferred to the lowest level of the triplet excited state of the guest material (phosphorescent material), and light emission is obtained (FIG. 2A). See Route B).

  Note that the process of Route A and Route B described above is referred to as ExTET (Exciplex-Triple Energy Transfer) in this specification and the like. As described above, the light-emitting element of one embodiment of the present invention can transfer energy from an exciplex to a phosphorescent material (guest material).

  In addition, one of the first organic compound and the second organic compound receives a hole, the other receives an electron, and rapidly forms an exciplex when they approach each other. Alternatively, when one is in an excited state, the other substance is quickly taken in to form an exciplex. Therefore, most excitons in the second light-emitting layer 114 exist as exciplexes. Since the exciplex has a smaller band gap than both the first organic compound and the second organic compound, the exciplex is formed by recombination of one hole and the other electron, thereby lowering the driving voltage. be able to.

<Light emitting mechanism of first light emitting layer>
In the first light-emitting layer 113, an excited state is formed by carrier recombination. Note that the first light-emitting layer 113 includes a host material and a fluorescent material. Since the host material is present in a large amount as compared with the fluorescent material, the excited state exists almost as an excited state of the host material. The ratio between the singlet excited state and the triplet excited state (hereinafter, exciton generation probability) generated by carrier recombination is about 1: 3.

First, T ₁ level of the host material for the case higher than the T ₁ level of the guest material, will be described below.

Energy transfer (triplet energy transfer) occurs from the triplet excited state of the host material to the guest material. However, since the guest material is a fluorescent material, the triplet excited state does not emit light in the visible light region. Therefore, the triplet excited state of the host material cannot be used as light emission. Therefore, when the T ₁ level of the host material is higher than the T ₁ level of the guest material, only about 25% of the injected carriers can be used for light emission at the maximum.

Next, FIG. 2B illustrates a correlation between energy levels of the host material and the fluorescent material in the first light-emitting layer 113 of one embodiment of the present invention. In addition, the notation and code | symbol in FIG. 2 (B) are as follows.
-Host: Host material-Guest: Fluorescent material-S _FH : Lowest level of singlet excited state of host material-T _FH : Lowest level of triplet excited state of host material-S _FG : Guest material (fluorescence Material) lowest level of singlet excited state T _FG : lowest level of triplet excited state of guest material (fluorescent material)

As shown in FIG. 2B, the T ₁ level of the guest material (T _FG in FIG. 2B) is higher than the T ₁ level of the host material (T _FH in FIG. 2B). It is a configuration.

In addition, as shown in FIG. 2B, triplet excitons collide with each other by triplet-triplet annihilation (TTA), and a part of the singlet excited state of the host material. _Is converted to the lowest level (S _FH ). Energy transfer from the lowest level (S _FH ) in the singlet excited state of the host material to the lowest level (S _FG ) in the singlet excited state of the guest material (fluorescent material) having a lower level than that. Occurred (see Route C in FIG. 2B), the fluorescent material emits light.

Note that since the T ₁ level of the host material is smaller than the T ₁ level of the guest material, T _FG transfers energy to T _FH without deactivation (see Route D shown in FIG. 2B), and TTA Used for

<Light emitting mechanism of first light emitting layer and second light emitting layer>
Although the light-emitting mechanisms of the first light-emitting layer 113 and the second light-emitting layer 114 have been described above, in the light-emitting element 100 of one embodiment of the present invention, the first light-emitting layer 113 and the second light-emitting layer are further provided. Even if energy transfer from the exciplex to the host material of the first light-emitting layer 113 (especially, energy transfer of triplet excited level) occurs at the interface of the layer 114, the triplet in the first light-emitting layer 113 is obtained. Excitation energy can be converted into luminescence.

Specifically, FIG. 3 shows the correlation of energy levels when TTA is used for the first light-emitting layer 113 and ExTET is used for the second light-emitting layer 114. In addition, the notation and code | symbol in FIG. 3 are as follows.
Fluorescence EML: fluorescent light emitting layer (first light emitting layer 113)
Phosphorescence EML: phosphorescent light emitting layer (second light emitting layer 114)
T _FH : lowest level of triplet excited state of host material S _FG : lowest level of singlet excited state of guest material (fluorescent material) T _FG : triplet excitation of guest material (fluorescent material) The lowest level of the state · S _PH : The lowest level of the singlet excited state of the host material (first organic compound) · T _PH : The lowest of the triplet excited state of the host material (first organic compound) level · T _PG: the lowest triplet excited state of the guest material (phosphorescent material) level · S _E: the lowest level · T _E of the singlet excited state of the _exciplex: triplet excited state of the exciplex Lowest level

As shown in FIG. 3, since the exciplex exists only in an excited state, exciton diffusion between the exciplex and the exciplex is unlikely to occur. The excitation levels (S _E , T _E ) of the exciplex are based on the excitation levels (S _PH , T _PH ) of the first organic compound (that is, the host material of the phosphorescent material) of the second light-emitting layer 114. Therefore, energy diffusion from the exciplex to the first organic compound does not occur. That is, since the exciton diffusion distance of the exciplex is short in the phosphorescent light emitting layer (second light emitting layer 114), the light emission efficiency of the phosphorescent light emitting layer (second light emitting layer 114) can be maintained. In addition, at the interface between the fluorescent light emitting layer (first light emitting layer 113) and the phosphorescent light emitting layer (second light emitting layer 114), one triplet excitation energy of the exciplex of the phosphorescent light emitting layer (second light emitting layer 114) is obtained. Part diffuses into the fluorescent light emitting layer (first light emitting layer 113), the triplet excitation energy of the fluorescent light emitting layer (first light emitting layer 113) generated by the diffusion is emitted through TTA. Energy loss can be reduced.

  As described above, the light-emitting element of one embodiment of the present invention has a light emission efficiency that exceeds the exciton generation probability by using ExTET for the second light-emitting layer 114 and TTA for the first light-emitting layer 113. Can be obtained. Therefore, a highly efficient light-emitting element can be provided.

  Note that in FIG. 1A, the first light-emitting layer 113 is provided on the first electrode 101 side that functions as an anode, and the second light-emitting layer 114 is provided on the second electrode 102 side that functions as a cathode. However, this stacking order may be reversed. Specifically, as in the light-emitting element 140 illustrated in FIG. 1B, the first light-emitting layer 113 is provided on the electrode side functioning as a cathode, and the second light-emitting layer 114 is provided on the electrode side functioning as an anode. It may be provided. In other words, the light-emitting element 140 has a structure in which the first light-emitting layer 113 is provided over the second light-emitting layer 114.

  The structure as shown in the light-emitting element 140 is preferable when a microcavity structure (described later) is employed because the optical path length of the second light-emitting layer 114 and / or the first light-emitting layer 113 can be easily adjusted. is there.

  Here, details of each structure of the light-emitting element 100 of one embodiment of the present invention are described below.

<Electrode>
The first electrode 101 and the second electrode 102 have a function of injecting holes and electrons into the first light-emitting layer 113 and the second light-emitting layer 114, respectively. These electrodes can be formed using a metal, an alloy, a conductive compound, a mixture or laminate of these. Aluminum is a typical example of the metal, and other transition metals such as silver, tungsten, chromium, molybdenum, copper, and titanium, alkali metals such as lithium and cesium, and Group 2 metals such as calcium and magnesium can be used. . A rare earth metal may be used as the transition metal. As the alloy, an alloy containing the above metal can be used, and examples thereof include MgAg and AlLi. Examples of the conductive compound include metal oxides such as indium tin oxide (Indium Tin Oxide). An inorganic carbon-based material such as graphene may be used as the conductive compound. As described above, the first electrode 101, the second electrode 102, or both may be formed by stacking a plurality of these materials.

  Light emission obtained from the first light-emitting layer 113 and the second light-emitting layer 114 is extracted through the first electrode 101, the second electrode 102, or both. Accordingly, at least one of these transmits visible light. In the case where a material with low light transmittance such as a metal or an alloy is used for the electrode from which light is extracted, the first electrode 101, the second electrode 102, or one of them has a thickness that allows visible light to pass therethrough. What is necessary is just to form a part. In this case, specifically, it is formed with a thickness of 1 nm to 10 nm.

<First light emitting layer>
The first light emitting layer 113 includes a host material and a fluorescent material. In the first light emitting layer 113, the host material is present in the largest amount by weight, and the fluorescent material is dispersed in the host material. S ₁ level of the host material is greater than S ₁ level of fluorescent material, T ₁ level of the host material is preferably smaller than the T ₁ level of the fluorescent material.

As a host material, an anthracene derivative or a tetracene derivative is preferable. This is because these derivatives have a large S ₁ level and a small T ₁ level. Specifically, 9-phenyl-3- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (PCzPA), 3- [4- (1-naphthyl) -phenyl] -9-phenyl -9H-carbazole (PCPN), 9- [4- (10-phenyl-9-anthracenyl) phenyl] -9H-carbazole (CzPA), 7- [4- (10-phenyl-9-anthryl) phenyl] -7H -Dibenzo [c, g] carbazole (cgDBCzPA), 6- [3- (9,10-diphenyl-2-anthryl) phenyl] -benzo [b] naphtho [1,2-d] furan (2mBnfPPA), 9- Phenyl-10- {4- (9-phenyl-9H-fluoren-9-yl) -biphenyl-4'-yl} -anthracene (FLPPA) and the like. The Alternatively, 5,12-diphenyltetracene, 5,12-bis (biphenyl-2-yl) tetracene, and the like can be given.

  Examples of the fluorescent material include pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, naphthalene derivatives, and the like. In particular, a pyrene derivative is preferable because of its high emission quantum yield. Specific examples of the pyrene derivative include N, N′-bis (3-methylphenyl) -N, N′-bis [3- (9-phenyl-9H-fluoren-9-yl) phenyl] pyrene-1,6. -Diamine (1,6 mM emFLPAPrn), N, N'-bis [4- (9-phenyl-9H-fluoren-9-yl) phenyl] -N, N'-diphenylpyrene-1,6-diamine (1,6FLPAPrn ), N, N′-bis (dibenzofuran-2-yl) -N, N′-diphenylpyrene-1,6-diamine (1,6FrAPrn), N, N′-bis (dibenzothiophen-2-yl)- N, N′-diphenylpyrene-1,6-diamine (1,6ThAPrn) and the like can be mentioned.

<Second light emitting layer>
The second light-emitting layer 114 includes a first organic compound, a second organic compound, and a phosphorescent material. Here, the first organic compound is used as a host material, and the second organic compound is used as an assist material.

In the second light-emitting layer 114, the host material (first organic compound) is present in the largest amount by weight ratio, and the phosphorescent material is dispersed in the host material. The T ₁ level of the host material (first organic compound) of the second light-emitting layer 114 is preferably larger than the T ₁ level of the fluorescent material of the first light-emitting layer 113.

  Examples of phosphorescent materials include iridium, rhodium, or platinum-based organometallic complexes, or metal complexes. Among these, organic iridium complexes such as iridium-based orthometal complexes are preferred. Examples of orthometalated ligands include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, and isoquinoline ligands. Can be mentioned. Examples of the metal complex include a platinum complex having a porphyrin ligand.

  The phosphorescent material is preferably a material having a peak in the yellow wavelength region. The emission spectrum of the material having a peak in the yellow wavelength region is preferably a material containing spectral components in the green and red wavelength regions.

  Host materials (first organic compounds) include zinc and aluminum metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, Examples include triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives, and the like. Other examples include aromatic amines and carbazole derivatives.

  The second organic compound (assist material) is a combination that can form an exciplex with the first organic compound. In this case, the first organic compound overlaps the absorption band of the triplet MLCT (Metal to Ligand Charge Transfer) transition of the phosphorescent material, more specifically, the absorption band on the longest wavelength side, more specifically, It is preferable to select the second organic compound and the phosphorescent material. As a result, a light emitting element with significantly improved luminous efficiency can be provided. However, in the case where a thermally activated delayed fluorescence (TADF) material is used instead of the phosphorescent material, it is preferable that the absorption band on the longest wavelength side is a singlet absorption band. The TADF material will be described later.

  There is no limitation on the emission colors of the first light emitting material and the second light emitting material, and they may be the same or different. Since the light emission obtained from each is mixed and taken out of the device, the light emitting device can give white light when, for example, the light emission colors of both are complementary colors. In consideration of the reliability of the light emitting element, the emission peak wavelength of the first light emitting material is preferably shorter than that of the second light emitting material. For example, it is preferable that the first light-emitting material emits blue light and the second light-emitting material emits yellow light.

<Other layers>
In addition, as illustrated in FIG. 1A, the light-emitting element 100 of one embodiment of the present invention may include a layer other than the first light-emitting layer 113 and the second light-emitting layer 114 described above. For example, a hole injection layer, a hole transport layer, an electron blocking layer, a hole blocking layer, an electron transport layer, an electron injection layer, and the like may be included. Each of these layers may be formed of a plurality of layers. These layers can reduce a carrier injection barrier, improve carrier transportability, or suppress a quenching phenomenon due to an electrode, and contribute to improvement of light emission efficiency and reduction of driving voltage. Each of these layers is formed by vapor deposition (including vacuum vapor deposition), printing (for example, relief printing, intaglio printing, gravure printing, lithographic printing, stencil printing, etc.), inkjet printing, coating It can be formed by using methods such as methods alone or in combination.

<Hole injection layer>
The hole injection layer 111 has a function of promoting hole injection by reducing a hole injection barrier from the first electrode 101, and is formed of, for example, a transition metal oxide, a phthalocyanine derivative, or an aromatic amine. . Examples of the transition metal oxide include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of the phthalocyanine derivative include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. High molecular compounds such as polythiophene and polyaniline can also be used. For example, self-doped polythiophene poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) is a typical example.

  As the hole-injecting layer 111, a composite material of a hole-transporting material and a material that exhibits an electron accepting property can be used. Alternatively, a stack of a layer containing a material showing electron accepting properties and a layer containing a hole transporting material may be used. Charges can be transferred between these materials in a steady state or in the presence of an electric field. Examples of the material exhibiting electron acceptability include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Transition metal oxides such as Group 4 to Group 8 metal oxides can also be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, and the like. Among these, molybdenum oxide is preferable because it is stable in the air, has a low hygroscopic property, and is easy to handle.

As the hole transporting material, a material having a hole transporting property higher than that of electrons can be used, and a material having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or more is preferable. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, and the like can be used. The hole transporting material may be a polymer compound.

<Hole transport layer>
The hole transport layer 112 is a layer including a hole transport material, and the materials exemplified as the material of the hole injection layer 111 can be used. Since the hole transport layer 112 has a function of transporting holes injected into the hole injection layer 111 to the first light-emitting layer 113, it is the same as the highest occupied orbital (HOMO) level of the hole injection layer 111. Alternatively, it is preferable to have a close HOMO level.

<Electron transport layer>
The electron transport layer 115 has a function of transporting electrons injected from the second electrode 102 through the electron injection layer 116 to the second light emitting layer 114. As the electron transporting material, a material having a higher electron transporting property than holes can be used, and a material having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or more is preferable. Specific examples include metal complexes having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, pyridine derivatives, and bipyridine derivatives. It is done.

<Electron injection layer>
The electron injection layer 116 has a function of promoting electron injection by reducing an electron injection barrier from the second electrode 102. For example, a group 1 metal, a group 2 metal, or an oxide, halide, or the like thereof A carbonate or the like can be used. Alternatively, a composite material of the electron transporting material described above and a material exhibiting an electron donating property can be used. Examples of the material exhibiting electron donating properties include Group 1 metals, Group 2 metals, and oxides thereof.

<Substrate, FET, etc.>
The light emitting element 100 may be manufactured over a substrate made of glass, plastic, or the like. As an order of manufacturing on the substrate, the layers may be sequentially stacked from the first electrode 101 side or may be sequentially stacked from the second electrode 102 side. Further, for example, a field effect transistor (FET) may be formed on a substrate made of glass, plastic, or the like, and a light-emitting element may be formed on an electrode electrically connected to the FET. Thus, an active matrix light-emitting device in which driving of the light-emitting element is controlled by the FET can be manufactured.

  In the above description, the light-emitting material included in the second light-emitting layer 114 is described as a phosphorescent material; however, the present invention is not limited to this. The light-emitting material included in the second light-emitting layer 114 may be any material that can convert triplet excitation energy into light emission. As a material capable of converting the triplet excitation energy into light emission, a TADF material can be cited in addition to a phosphorescent material. Therefore, the portion described as phosphorescent material may be read as TADF material. A TADF material is a material that can up-convert a triplet excited state to a singlet excited state with a slight amount of thermal energy (interverse crossing) and efficiently emits light (fluorescence) from the singlet excited state. That is. As a condition for efficiently obtaining thermally activated delayed fluorescence, the energy difference between the triplet excited level and the singlet excited level is 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. Can be mentioned.

  Note that this embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 2)
In this embodiment, a light-emitting element having a structure different from that of the light-emitting elements 100 and 140 described in Embodiment 1 will be described below with reference to FIGS. 4A is a schematic cross-sectional view of the light-emitting element 150 of one embodiment of the present invention, and FIG. 4B is a schematic cross-sectional view of the light-emitting element 160 of one embodiment of the present invention.

  The light emitting element 150 is different from the light emitting element 100 in that the separation layer 120 is provided between the first light emitting layer 113 and the second light emitting layer 114. The separation layer 120 is in contact with the first light-emitting layer 113 and the second light-emitting layer 114. Since the structure of the other layers is the same as that of the first embodiment, description thereof is omitted.

  The separation layer 120 transfers energy by a Dexter mechanism from the excited state of the first organic compound or phosphorescent material generated in the second light-emitting layer 114 to the host material or fluorescent material in the first light-emitting layer 113 ( In particular, it is provided to prevent triplet energy transfer). Therefore, the separation layer only needs to have a thickness of about several nm. Specifically, the thickness is 0.1 nm to 20 nm, or 1 nm to 10 nm, or 1 nm to 5 nm.

  The separation layer 120 may be made of a single material, but may contain both a hole transporting material and an electron transporting material. In the case of a single material, a bipolar material may be used. Here, the bipolar material refers to a material having a mobility ratio of electrons and holes of 100 or less. As a material included in the separation layer 120, the hole-transporting material, the electron-transporting material, or the like exemplified in Embodiment 1 can be used. Further, the material included in the separation layer 120 or at least one of them may be formed using the same material as the host material (first organic compound) of the second light-emitting layer 114. This facilitates the production of the light emitting element and reduces the driving voltage.

  For example, when the separation layer 120 is formed of the same material as the host material (first organic compound) and the assist material (second organic compound) of the second light-emitting layer 114, The second light-emitting layer 114 is stacked through the layer (separation layer 120) that does not include the phosphorescent material of the second light-emitting layer 114. With such a structure, the separation layer 120 and the second light-emitting layer 114 can be deposited with or without a phosphorescent material. In other words, the separation layer 120 has a region not containing a phosphorescent material, and the second light-emitting layer 114 has a region containing a phosphorescent material. With such a structure, the separation layer 120 and the second light-emitting layer 114 can be formed in the same chamber. Thereby, manufacturing cost can be reduced.

Alternatively, at least one of the materials included in the separation layer 120 or at least one of them may have a higher T ₁ level than the host material (first organic compound) of the second light-emitting layer 114.

  The recombination region can be adjusted by adjusting the mixing ratio of the hole transporting material and the electron transporting material, whereby the emission color can be controlled. For example, in the case where the first electrode 101 and the second electrode 102 are an anode and a cathode, respectively, the recombination region is increased from the first electrode 101 side to the second electrode by increasing the ratio of the hole transport material of the separation layer 120. It can shift to the electrode 102 side. Thereby, the contribution of light emission from the second light emitting layer 114 can be increased. Conversely, by increasing the proportion of the electron transport material, the recombination region can be shifted from the second electrode 102 side to the first electrode 101 side, and the contribution of light emission from the first light-emitting layer 113 is increased. be able to. When the light emission colors from the first light-emitting layer 113 and the second light-emitting layer 114 are different, the light emission color of the entire light-emitting element can be changed.

  The hole transporting material and the electron transporting material may form an exciplex in the separation layer 120, thereby effectively preventing exciton diffusion. Specifically, energy transfer from the excited state of the host material (first organic compound) or phosphorescent material of the second light-emitting layer 114 to the host material or fluorescent material of the first light-emitting layer 113 can be prevented. .

  Further, similarly to the light-emitting element 140 described in Embodiment 1, the first light-emitting layer 113 may be positioned on the second light-emitting layer 114. Specifically, as in the light-emitting element 160 illustrated in FIG. 4B, the second light-emitting layer 114 is provided over the hole-transport layer 112, and the first light-emitting layer is interposed therebetween with the separation layer 120 interposed therebetween. 113 may be provided.

  The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 3)
In this embodiment, a light-emitting element which is one embodiment of the present invention will be described with reference to FIGS. Note that FIG. 5 is a schematic cross-sectional view illustrating a light-emitting element 170 of one embodiment of the present invention.

  The light-emitting element 170 includes a plurality of light-emitting units (the first light-emitting unit 131 and the second light-emitting unit 132 in FIG. 5) between the first electrode 101 and the second electrode 102. One light emitting unit has a structure similar to that of the EL layer 130 shown in FIG. In other words, the light-emitting element 100 illustrated in FIG. 1 includes one light-emitting unit, and the light-emitting element 170 includes a plurality of light-emitting units.

  Further, in the light-emitting element 170 illustrated in FIG. 5, the first light-emitting unit 131 and the second light-emitting unit 132 are stacked, and charge is generated between the first light-emitting unit 131 and the second light-emitting unit 132. A layer 133 is provided. Note that the first light-emitting unit 131 and the second light-emitting unit 132 may have the same configuration or different configurations.

The charge generation layer 133 contains a composite material of an organic compound and a metal oxide. As the composite material, a composite material that can be used for the hole-injection layer 111 described above may be used. As the organic compound, various compounds such as an aromatic amine compound, a carbazole compound, an aromatic hydrocarbon, and a high molecular compound (oligomer, dendrimer, polymer, etc.) can be used. Note that an organic compound having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher is preferably used. Note that other than these substances, any substance that has a property of transporting more holes than electrons may be used. Since the composite material of an organic compound and a metal oxide is excellent in carrier injecting property and carrier transporting property, low voltage driving and low current driving can be realized. Note that when the surface of the light emitting unit on the anode side is in contact with the charge generation layer 133, the charge generation layer 133 can also serve as a hole transport layer of the light emission unit. It does not have to be provided.

  Note that the charge generation layer 133 may be formed as a stacked structure in which a layer including a composite material of an organic compound and a metal oxide and a layer formed using another material are combined. For example, a layer including a composite material of an organic compound and a metal oxide may be combined with a layer including one compound selected from electron donating substances and a compound having a high electron transporting property. Alternatively, a layer including a composite material of an organic compound and a metal oxide may be combined with a transparent conductive film.

  Note that the charge generation layer 133 sandwiched between the first light-emitting unit 131 and the second light-emitting unit 132 has electrons applied to one light-emitting unit when voltage is applied to the first electrode 101 and the second electrode 102. What is necessary is just to inject and inject holes into the other light emitting unit. For example, in FIG. 5, when a voltage is applied so that the potential of the first electrode 101 is higher than the potential of the second electrode 102, the charge generation layer 133 causes the first light emitting unit 131 to emit electrons. What is necessary is just to inject and inject holes into the second light emitting unit 132.

  5 illustrates the light-emitting element having two light-emitting units, the present invention can be similarly applied to a light-emitting element in which three or more light-emitting units are stacked. Like the light-emitting element 170, a plurality of light-emitting units are arranged between a pair of electrodes separated by a charge generation layer, enabling high-intensity light emission while maintaining a low current density and realizing a longer-lifetime element. it can. In addition, a light-emitting device that can be driven at a low voltage and has low power consumption can be realized.

  Note that by applying the structure of the EL layer 130 to at least one of the plurality of units, the manufacturing process of the unit can be reduced, and thus a multicolor light emitting element advantageous for practical use is provided. be able to.

  Note that the above structure can be combined with any of the other embodiments and the other structures in this embodiment as appropriate.

(Embodiment 4)
In this embodiment, a light-emitting device using the light-emitting element described in any of Embodiments 1 to 3 will be described with reference to FIGS.

  6A is a top view illustrating the light-emitting device 600, and FIG. 6B is a cross-sectional view taken along the dashed-dotted line AB and the dashed-dotted line CD in FIG. 6A. The light-emitting device 600 includes a driver circuit portion (a source line driver circuit portion 601 and a gate line driver circuit portion 603) and a pixel portion 602. Note that the source line driver circuit portion 601, the gate line driver circuit portion 603, and the pixel portion 602 have a function of controlling light emission of the light-emitting element.

  In addition, the light-emitting device 600 includes an element substrate 610, a sealing substrate 604, a sealing material 605, a region 607 surrounded by the sealing material 605, a lead wiring 608, and an FPC 609.

  Note that the lead wiring 608 is a wiring for transmitting a signal input to the source line driver circuit portion 601 and the gate line driver circuit portion 603, and a video signal, a clock signal, a start signal, and the like from the FPC 609 serving as an external input terminal. Receive a reset signal. Note that only the FPC 609 is illustrated here, but a printed wiring board (PWB) may be attached to the FPC 609.

  In the source line driver circuit portion 601, a CMOS circuit in which an n-channel FET 623 and a p-channel FET 624 are combined is formed. Note that the source line driver circuit portion 601 or the gate line driver circuit portion 603 may be formed using various CMOS circuits, NMOS circuits, or PMOS circuits. In this embodiment mode, a driver integrated type in which a driver circuit portion is formed over a substrate is shown; however, this is not always necessary, and the driver circuit portion can be formed outside the substrate.

  The pixel portion 602 includes a switching FET 611, a current control FET 612, and a first electrode 613 electrically connected to the drain of the current control FET 612. Note that an insulator 614 is formed so as to cover an end portion of the first electrode 613. As the insulator 614, a positive photosensitive acrylic resin film can be used.

  In order to improve the coverage, a curved surface having a curvature is formed at the upper end or the lower end of the insulator 614. For example, in the case where positive photosensitive acrylic is used as a material for the insulator 614, it is preferable that only the upper end portion of the insulator 614 has a curved surface with a curvature radius (0.2 μm to 3 μm). As the insulator 614, either a negative photosensitive resin or a positive photosensitive resin can be used.

  In addition, the structure of FET (FET611,612,623,624) is not specifically limited. For example, a staggered transistor may be used. There is no particular limitation on the polarity of the transistor, and a structure including N-type and P-type transistors and a structure including only one of an N-type transistor and a P-type transistor may be used. There is no particular limitation on the crystallinity of a semiconductor film used for the transistor. For example, an amorphous semiconductor film or a crystalline semiconductor film can be used. As the semiconductor material, a Group 13 (gallium or the like) semiconductor, a Group 14 (silicon or the like) semiconductor, a compound semiconductor (including an oxide semiconductor), an organic semiconductor, or the like can be used. As the transistor, for example, an oxide semiconductor with an energy gap of 2 eV or more, preferably 2.5 eV or more, more preferably 3 eV or more can be used because off-state current of the transistor can be reduced. Examples of the oxide semiconductor include In—Ga oxide and In—M—Zn oxide (M is Al, Ga, Y, Zr, La, Ce, or Nd).

  An EL layer 616 and a second electrode 617 are formed over the first electrode 613. Note that the first electrode 613 functions as an anode, and the second electrode 617 functions as a cathode.

  The EL layer 616 is formed by vapor deposition (including vacuum vapor deposition), printing (for example, letterpress printing, intaglio printing, gravure printing, planographic printing, stencil printing, etc.), ink jet printing, coating, etc. It can form by the method of. The EL layer 616 includes the structure described in Embodiment Modes 1 to 3. Further, as another material forming the EL layer 616, a low molecular compound or a high molecular compound (including an oligomer and a dendrimer) may be used.

  Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. A light-emitting element 618 is a light-emitting element having the structure of Embodiments 1 to 3. Note that in the case where a plurality of light-emitting elements are formed, the pixel portion may include both the light-emitting elements described in Embodiments 1 to 3 and light-emitting elements having other structures.

  Further, the sealing substrate 604 is attached to the element substrate 610 with the sealant 605, whereby the light-emitting element 618 is provided in the region 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. ing. Note that the region 607 is filled with a filler, and may be filled with a sealant 605 in addition to an inert gas (such as nitrogen or argon). When a recess is formed in the sealing substrate and a desiccant (not shown) is provided there, deterioration due to the influence of moisture can be suppressed, which is a preferable configuration.

  Note that an epoxy resin or glass frit is preferably used for the sealant 605. Moreover, it is desirable that these materials are materials that do not transmit moisture and oxygen as much as possible. In addition to a glass substrate or a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic, or the like can be used as a material for the sealing substrate 604.

  As described above, a light-emitting device manufactured using the light-emitting element described in any of Embodiments 1 to 3 can be obtained.

  Since the light-emitting device 600 in this embodiment uses the light-emitting element described in any of Embodiments 1 to 3, a light-emitting device having favorable characteristics can be obtained. Specifically, the light-emitting elements described in Embodiments 1 to 3 are light-emitting elements with favorable light-emitting efficiency, and can be a light-emitting device with low power consumption. Further, the light-emitting element is easily mass-produced, and an inexpensive light-emitting device can be provided.

  Next, FIGS. 7A and 7B illustrate examples of cross-sectional views of a light-emitting device which is formed into a full color by forming a light-emitting element that emits white light and providing a colored layer (color filter) or the like.

  7A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003, gate electrodes 1006, 1007, and 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, and a pixel portion. 1040, a driver circuit portion 1041, light emitting element first electrodes 1024Y, 1024R, 1024G, and 1024B, a partition wall 1025, an EL layer 1028, a light emitting element second electrode 1026, a sealing substrate 1031, a sealant 1032, and the like are illustrated. ing.

  In FIG. 7A, colored layers (a red colored layer 1034R, a green colored layer 1034G, a blue colored layer 1034B, and a yellow colored layer 1034Y) are provided over a transparent substrate 1033. Further, a black layer (black matrix) 1035 may be further provided. The transparent base material 1033 provided with the coloring layer and the black layer is aligned and fixed to the substrate 1001. Note that the colored layer and the black layer are covered with an overcoat layer 1036. In FIG. 7A, since light transmitted through the colored layer is red, blue, green, and yellow, an image can be expressed with pixels of four colors.

  FIG. 7B illustrates an example in which a colored layer (a red colored layer 1034R, a green colored layer 1034G, or a blue colored layer 1034B) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020. . As described above, the coloring layer may be provided between the substrate 1001 and the sealing substrate 1031. Note that since the light-emitting element of one embodiment of the present invention can emit a yellow wavelength, a structure in which a yellow colored layer is not provided as illustrated in FIG. 7B may be employed.

  In the light-emitting device described above, a light-emitting device having a structure in which light is extracted to the substrate 1001 side where the FET is formed (bottom emission type) is used. However, a structure in which light is extracted to the sealing substrate 1031 side (top-emission type). ).

  An example of a cross-sectional view of a top emission type light emitting device is shown in FIG. In this case, a substrate that does not transmit light can be used as the substrate 1001. Until the connection electrode for connecting the FET and the anode of the light emitting element is manufactured, it is formed in the same manner as the bottom emission type light emitting device. Thereafter, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. This insulating film may play a role of planarization. The third interlayer insulating film 1037 can be formed using various other materials in addition to the same material as the second interlayer insulating film.

  The first electrodes 1024Y, 1024R, 1024G, and 1024B of the light-emitting elements are anodes here, but may be cathodes. In the case of a top emission light-emitting device as shown in FIG. 8, the first electrodes 1024Y, 1024R, 1024G, and 1024B are preferably used as reflective electrodes. The EL layer 1028 has a structure as described for the EL layer 130 in Embodiments 1 to 3, and has an element structure in which white light emission can be obtained.

  In FIG. 8, the second electrode 1026 is provided over the EL layer 1028. For example, the second electrode 1026 is a semi-transmissive / semi-reflective electrode, and the micro optical resonator using the resonance effect of light between the first electrodes 1024Y, 1024R, 1024G, and 1024B and the second electrode 1026 is used. A (microcavity) structure may be adopted to increase the light intensity at a specific wavelength.

  In the top emission structure as shown in FIG. 8, sealing is performed with a sealing substrate 1031 provided with colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B, and yellow colored layer 1034Y). be able to. A black layer 1035 may be provided on the sealing substrate 1031 so as to be positioned between the pixels. The colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B, and yellow colored layer 1034Y) and the black layer 1035 may be covered with an overcoat layer (not shown). Note that a light-transmitting substrate is used as the sealing substrate 1031.

  8 illustrates a light-emitting element that can emit white light and a structure in which a colored layer is provided on the light-emitting element, the invention is not limited to this. For example, as shown in FIG. 9A, a blue colored layer is provided by providing a light emitting element that can emit white light, a red colored layer 1034R, a green colored layer 1034G, and a yellow colored layer 1034Y. In which full color display is performed with four colors of red, green, blue, and yellow, or as shown in FIG. 9B, a light emitting element capable of obtaining white light emission, and a red colored layer 1034R. And a green colored layer 1034G may be provided, and a full color display may be performed with four colors of red, green, blue, and yellow without providing blue and yellow colored layers. As shown in FIG. 8, when a light emitting element capable of obtaining white light emission and a structure in which a colored layer is provided on each of the light emitting elements, an effect of suppressing external light reflection can be obtained. On the other hand, as shown in FIG. 9B, a light emitting element capable of obtaining white light emission, a red colored layer and a green colored layer are provided, and a blue and yellow colored layer is not provided. Since the energy loss of the light emitted from the light emitting element is small, the power consumption can be reduced.

  In addition, as shown in FIG. 10A, a light-emitting element capable of obtaining white light emission, and a structure in which a colored layer is provided on the light-emitting element to perform full-color display in three colors of red, green, and blue, Alternatively, as illustrated in FIG. 10B, a light-emitting element that can emit white light, a red colored layer 1034R, and a green colored layer 1034G are provided, and a blue colored layer is not provided. A full-color display may be performed with three colors of green and blue.

  9A and 9B and FIGS. 10A and 10B are schematic cross-sectional views illustrating a light-emitting device of one embodiment of the present invention. The driver circuit portion 1041 and the peripheral portion illustrated in FIG. For example, 1042 is omitted. Further, not only in FIG. 8, but also in FIGS. 9 and 10, a microcavity structure may be adopted.

  Since the light-emitting device described in any of Embodiments 1 to 3 is used for the light-emitting device in this embodiment, a light-emitting device having favorable characteristics can be obtained. Specifically, the light-emitting elements described in Embodiments 1 to 3 are light-emitting elements with favorable light-emitting efficiency, and can be a light-emitting device with low power consumption. In addition, by combining the light-emitting element described in any of Embodiments 1 to 3 with a colored layer such as a color filter, an optimal element structure in which white light emission can be obtained can be obtained. In addition, the light-emitting element described in any of Embodiments 1 to 3 has a light-emitting structure that is easily mass-produced, and can provide an inexpensive light-emitting device.

  Note that the above structure can be combined with any of the other embodiments and the other structures in this embodiment as appropriate.

(Embodiment 5)
In this embodiment, a display device including the light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

  11A is a block diagram illustrating a display device of one embodiment of the present invention, and FIG. 11B is a circuit diagram illustrating a pixel circuit included in the display device of one embodiment of the present invention. is there.

  A display device illustrated in FIG. 11A includes a region having a pixel of a display element (hereinafter referred to as a pixel portion 802) and a circuit portion (hereinafter, referred to as a pixel portion 802) having a circuit for driving the pixel. , A driver circuit portion 804), a circuit having an element protection function (hereinafter referred to as a protection circuit 806), and a terminal portion 807. Note that the protection circuit 806 may not be provided.

  Part or all of the driver circuit portion 804 is preferably formed over the same substrate as the pixel portion 802. Thereby, the number of parts and the number of terminals can be reduced. When part or all of the driver circuit portion 804 is not formed over the same substrate as the pixel portion 802, part or all of the driver circuit portion 804 is formed by COG or TAB (Tape Automated Bonding). Can be implemented.

  The pixel portion 802 includes a circuit (hereinafter referred to as a pixel circuit 801) for driving a plurality of display elements arranged in X rows (X is a natural number of 2 or more) and Y columns (Y is a natural number of 2 or more). The driver circuit portion 804 outputs a signal (scanning signal) for selecting a pixel (hereinafter referred to as a gate driver 804a), and a circuit for supplying a signal (data signal) for driving a display element of the pixel (data signal). Hereinafter, a driver circuit such as a source driver 804b) is provided.

  The gate driver 804a includes a shift register and the like. The gate driver 804a receives a signal for driving the shift register via the terminal portion 807 and outputs a signal. For example, the gate driver 804a receives a start pulse signal, a clock signal, and the like and outputs a pulse signal. The gate driver 804a has a function of controlling the potential of a wiring to which a scan signal is supplied (hereinafter referred to as scan lines GL_1 to GL_X). Note that a plurality of gate drivers 804a may be provided, and the scanning lines GL_1 to GL_X may be divided and controlled by the plurality of gate drivers 804a. Alternatively, the gate driver 804a has a function of supplying an initialization signal. However, the present invention is not limited to this, and the gate driver 804a can supply another signal.

  The source driver 804b includes a shift register and the like. In addition to a signal for driving the shift register, the source driver 804b receives a signal (image signal) as a source of a data signal through the terminal portion 807. The source driver 804b has a function of generating a data signal to be written in the pixel circuit 801 based on the image signal. The source driver 804b has a function of controlling output of a data signal in accordance with a pulse signal obtained by inputting a start pulse, a clock signal, or the like. The source driver 804b has a function of controlling the potential of a wiring to which a data signal is supplied (hereinafter referred to as data lines DL_1 to DL_Y). Alternatively, the source driver 804b has a function of supplying an initialization signal. However, the present invention is not limited to this, and the source driver 804b can supply another signal.

  The source driver 804b is configured using, for example, a plurality of analog switches. The source driver 804b can output a signal obtained by time-dividing an image signal as a data signal by sequentially turning on a plurality of analog switches. Further, the source driver 804b may be configured using a shift register or the like.

  Each of the plurality of pixel circuits 801 receives a pulse signal through one of the plurality of scanning lines GL to which the scanning signal is applied, and receives the data signal through one of the plurality of data lines DL to which the data signal is applied. Entered. Also. In each of the plurality of pixel circuits 801, writing and holding of the data signal is controlled by the gate driver 804a. For example, the pixel circuit 801 in the m-th row and the n-th column receives a pulse signal from the gate driver 804a through the scanning line GL_m (m is a natural number equal to or less than X), and the data line DL_n (n Is a natural number less than or equal to Y), a data signal is input from the source driver 804b.

  The protection circuit 806 illustrated in FIG. 11A is connected to, for example, the scanning line GL that is a wiring between the gate driver 804a and the pixel circuit 801. Alternatively, the protection circuit 806 is connected to the data line DL that is a wiring between the source driver 804 b and the pixel circuit 801. Alternatively, the protection circuit 806 can be connected to a wiring between the gate driver 804 a and the terminal portion 807. Alternatively, the protection circuit 806 can be connected to a wiring between the source driver 804 b and the terminal portion 807. Note that the terminal portion 807 is a portion where a terminal for inputting a power supply, a control signal, and an image signal from an external circuit to the display device is provided.

  The protection circuit 806 is a circuit that brings a wiring into a conductive state when a potential outside a certain range is applied to the wiring to which the protection circuit 806 is connected.

  As shown in FIG. 11A, by providing a protection circuit 806 in each of the pixel portion 802 and the driver circuit portion 804, resistance of the display device to an overcurrent generated by ESD (Electro Static Discharge) is increased. be able to. However, the configuration of the protection circuit 806 is not limited thereto, and for example, a configuration in which the protection circuit 806 is connected to the gate driver 804a or a configuration in which the protection circuit 806 is connected to the source driver 804b may be employed. Alternatively, the protective circuit 806 can be connected to the terminal portion 807.

  FIG. 11A illustrates an example in which the driver circuit portion 804 is formed using the gate driver 804a and the source driver 804b; however, the present invention is not limited to this structure. For example, only the gate driver 804a may be formed and a substrate on which a separately prepared source driver circuit is formed (for example, a driver circuit substrate formed of a single crystal semiconductor film or a polycrystalline semiconductor film) may be mounted.

  In addition, the plurality of pixel circuits 801 illustrated in FIG. 11A can have a structure illustrated in FIG.

  A pixel circuit 801 illustrated in FIG. 11B includes transistors 852 and 854, a capacitor 862, and a light-emitting element 872.

  One of a source electrode and a drain electrode of the transistor 852 is electrically connected to a wiring to which a data signal is supplied (hereinafter referred to as a signal line DL_n). Further, the gate electrode of the transistor 852 is electrically connected to a wiring to which a gate signal is supplied (hereinafter referred to as a scanning line GL_m).

  The transistor 852 has a function of controlling data writing of the data signal by being turned on or off.

  One of the pair of electrodes of the capacitor 862 is electrically connected to a wiring to which a potential is applied (hereinafter referred to as a potential supply line VL_a), and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 852. Is done.

  The capacitor 862 functions as a storage capacitor for storing written data.

  One of a source electrode and a drain electrode of the transistor 854 is electrically connected to the potential supply line VL_a. Further, the gate electrode of the transistor 854 is electrically connected to the other of the source electrode and the drain electrode of the transistor 852.

  One of an anode and a cathode of the light-emitting element 872 is electrically connected to the potential supply line VL_b, and the other is electrically connected to the other of the source electrode and the drain electrode of the transistor 854.

  As the light-emitting element 872, the light-emitting element described in any of Embodiments 1 to 3 can be used.

  Note that one of the potential supply line VL_a and the potential supply line VL_b is supplied with the high power supply potential VDD, and the other is supplied with the low power supply potential VSS.

  In the display device including the pixel circuit 801 in FIG. 11B, for example, the pixel circuits 801 in each row are sequentially selected by the gate driver 804a illustrated in FIG. Write.

  The pixel circuit 801 in which data is written is brought into a holding state when the transistor 852 is turned off. Further, the amount of current flowing between the source electrode and the drain electrode of the transistor 854 is controlled in accordance with the potential of the written data signal, and the light-emitting element 872 emits light with luminance corresponding to the flowing current amount. By sequentially performing this for each row, an image can be displayed.

  The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 6)
In this embodiment, a display module and an electronic device each including the light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

  A display module 8000 illustrated in FIG. 12 includes a touch panel 8004 connected to the FPC 8003, a display panel 8006 connected to the FPC 8005, a frame 8009, a printed board 8010, and a battery 8011 between an upper cover 8001 and a lower cover 8002.

  The light-emitting device of one embodiment of the present invention can be used for the display panel 8006, for example.

  The shapes and dimensions of the upper cover 8001 and the lower cover 8002 can be changed as appropriate in accordance with the sizes of the touch panel 8004 and the display panel 8006.

  As the touch panel 8004, a resistive touch panel or a capacitive touch panel can be used by being superimposed on the display panel 8006. In addition, the counter substrate (sealing substrate) of the display panel 8006 can have a touch panel function. In addition, an optical sensor can be provided in each pixel of the display panel 8006 to provide an optical touch panel.

  The frame 8009 has a function as an electromagnetic shield for blocking electromagnetic waves generated by the operation of the printed board 8010 in addition to a protective function of the display panel 8006. The frame 8009 may have a function as a heat sink.

  The printed board 8010 includes a power supply circuit, a signal processing circuit for outputting a video signal and a clock signal. As a power supply for supplying power to the power supply circuit, an external commercial power supply may be used, or a power supply using a battery 8011 provided separately may be used. The battery 8011 can be omitted when a commercial power source is used.

  The display module 8000 may be additionally provided with a member such as a polarizing plate, a retardation plate, or a prism sheet.

  13A to 13G illustrate electronic devices. These electronic devices include a housing 9000, a display portion 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), a connection terminal 9006, and a sensor 9007 (force, displacement, position, speed, acceleration, angular velocity, Function to measure or detect rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared A microphone 9008, and the like.

  The electronic devices illustrated in FIGS. 13A to 13G can have a variety of functions. For example, a function for displaying various information (still images, moving images, text images, etc.) on the display unit, a touch sensor function, a function for displaying a calendar, date or time, etc., a function for controlling processing by various software (programs) , Wireless communication function, function to connect to various computer networks using wireless communication function, function to transmit or receive various data using wireless communication function, read program or data recorded in recording medium A function of displaying on the display portion can be provided. Note that the functions of the electronic devices illustrated in FIGS. 13A to 13G are not limited to these, and can have various functions. Although not illustrated in FIGS. 13A to 13G, the electronic device may have a plurality of display portions. In addition, the electronic device is equipped with a camera, etc., to capture still images, to capture moving images, to store captured images on a recording medium (externally or built into the camera), and to display captured images on the display unit And the like.

  Details of the electronic devices illustrated in FIGS. 13A to 13G are described below.

  FIG. 13A is a perspective view showing a portable information terminal 9100. A display portion 9001 included in the portable information terminal 9100 has flexibility. Therefore, the display portion 9001 can be incorporated along the curved surface of the curved housing 9000. Further, the display portion 9001 includes a touch sensor and can be operated by touching the screen with a finger, a stylus, or the like. For example, an application can be activated by touching an icon displayed on the display unit 9001.

  FIG. 13B is a perspective view showing the portable information terminal 9101. The portable information terminal 9101 has one or a plurality of functions selected from, for example, a telephone, a notebook, an information browsing device, or the like. Specifically, it can be used as a smartphone. Note that the portable information terminal 9101 is illustrated with the speaker 9003, the connection terminal 9006, the sensor 9007, and the like omitted, but can be provided at the same position as the portable information terminal 9100 illustrated in FIG. Further, the portable information terminal 9101 can display characters and image information on the plurality of surfaces. For example, three operation buttons 9050 (also referred to as operation icons or simply icons) can be displayed on one surface of the display portion 9001. Further, information 9051 indicated by a broken-line rectangle can be displayed on another surface of the display portion 9001. As an example of the information 9051, a display for notifying an incoming call such as an e-mail, SNS (social networking service), a telephone call, a title such as an e-mail or SNS, a sender name such as an e-mail or SNS, a date and time, and a time , Battery level, antenna reception strength and so on. Alternatively, an operation button 9050 or the like may be displayed instead of the information 9051 at a position where the information 9051 is displayed.

  FIG. 13C is a perspective view showing the portable information terminal 9102. The portable information terminal 9102 has a function of displaying information on three or more surfaces of the display portion 9001. Here, an example is shown in which information 9052, information 9053, and information 9054 are displayed on different planes. For example, the user of the portable information terminal 9102 can check the display (information 9053 here) in a state where the portable information terminal 9102 is stored in the chest pocket of clothes. Specifically, the telephone number or name of the caller of the incoming call is displayed at a position where it can be observed from above portable information terminal 9102. The user can check the display and determine whether to receive a call without taking out the portable information terminal 9102 from the pocket.

  FIG. 13D is a perspective view showing a wristwatch-type portable information terminal 9200. The portable information terminal 9200 can execute various applications such as a mobile phone, electronic mail, text browsing and creation, music playback, Internet communication, and computer games. Further, the display portion 9001 is provided with a curved display surface, and can perform display along the curved display surface. In addition, the portable information terminal 9200 can execute short-range wireless communication with a communication standard. For example, it is possible to talk hands-free by communicating with a headset capable of wireless communication. In addition, the portable information terminal 9200 includes a connection terminal 9006 and can directly exchange data with other information terminals via a connector. Charging can also be performed through the connection terminal 9006. Note that the charging operation may be performed by wireless power feeding without using the connection terminal 9006.

  13E, 13F, and 13G are perspective views illustrating a foldable portable information terminal 9201. FIG. 13E is a perspective view of a state in which the portable information terminal 9201 is expanded, and FIG. 13F is a state in the middle of changing from one of the expanded state or the folded state of the portable information terminal 9201 to the other. FIG. 13G is a perspective view of the portable information terminal 9201 folded. The portable information terminal 9201 is excellent in portability in the folded state, and in the expanded state, the portable information terminal 9201 is excellent in display listability due to a seamless wide display area. A display portion 9001 included in the portable information terminal 9201 is supported by three housings 9000 connected by a hinge 9055. By bending between the two housings 9000 via the hinge 9055, the portable information terminal 9201 can be reversibly deformed from the expanded state to the folded state. For example, the portable information terminal 9201 can be bent with a curvature radius of 1 mm to 150 mm.

  The electronic device described in this embodiment includes a display portion for displaying some information. Note that the light-emitting device of one embodiment of the present invention can also be applied to an electronic device having no display portion. In addition, in the display portion of the electronic device described in this embodiment, an example of a configuration that has flexibility and can display along a curved display surface, or a configuration of a foldable display portion is given. However, the present invention is not limited to this, and may have a configuration in which display is performed on a flat portion without having flexibility.

  The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 7)
In this embodiment, an example of a lighting device to which the light-emitting device which is one embodiment of the present invention is applied will be described with reference to FIGS.

  FIG. 14 illustrates an example in which the light-emitting device is used as an indoor lighting device 8501. Note that since the light-emitting device can have a large area, a large-area lighting device can also be formed. In addition, by using a housing having a curved surface, the lighting device 8502 in which the light-emitting region has a curved surface can be formed. A light-emitting element included in the light-emitting device described in this embodiment has a thin film shape, and the degree of freedom in designing a housing is high. Therefore, it is possible to form a lighting device with various designs. Further, a large lighting device 8503 may be provided on the indoor wall surface. Alternatively, the lighting devices 8501, 8502, and 8503 may be provided with touch sensors to turn on or off the light-emitting device.

  Further, by using the light-emitting device for the surface of the table, the lighting device 8504 having a function as a table can be obtained. Note that a lighting device having a function as furniture can be obtained by using a light-emitting device for part of other furniture.

  As described above, various lighting devices to which the light-emitting device is applied can be obtained. Note that these lighting devices are included in one embodiment of the present invention.

  The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

  In this example, an example of manufacturing a light-emitting element which is one embodiment of the present invention will be described. 15A and 15B are schematic cross-sectional views of light-emitting elements (light-emitting elements 1 to 4) manufactured in this example, Table 1 shows details of the element structure, and the structures and abbreviations of the compounds used are as follows. Shown in

<1-1. Production of Light-Emitting Element 1>
Indium tin oxide containing silicon oxide (ITSO (Indium Tin SiO ₂ Doped Oxide), film thickness 110 nm, area 2 mm × 2 mm) formed over the glass substrate 500 is used as the first electrode 501, and 1, 3 , 5-tri (dibenzothiophen-4-yl) benzene (DBT3P-II) and molybdenum oxide (MoO ₃ ) so that the weight ratio (DBT3P-II: MoO ₃ ) is 2: 1 and the film thickness is 40 nm. The hole injection layer 511 was formed by vapor deposition. Note that co-evaporation is an evaporation method in which a plurality of different substances are simultaneously evaporated from different evaporation sources.

  On the hole injection layer 511, 3- [4- (9-phenanthryl) -phenyl] -9-phenyl-9H-carbazole (PCPPn) is deposited to a thickness of 20 nm to form the hole transport layer 512. did.

  7- [4- (10-phenyl-9-anthryl) phenyl] -7H-dibenzo [c, g] carbazole (cgDBCzPA) and N, N′-bis (3-methylphenyl) on the hole transport layer 512 -N, N'-bis [3- (9-phenyl-9H-fluoren-9-yl) phenyl] pyrene-1,6-diamine (1,6mMemFLPAPrn) in a weight ratio (cgDBCzPA: 1,6mMemFLPAPrn) is 1: The first light-emitting layer 513 was formed by co-evaporation to a thickness of 0.02 and 10 nm. Note that in the first light-emitting layer 513, cgDBCzPA is a host material, and 1,6 mM emFLPAPrn is a fluorescent material (guest material).

2- [3 ′-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (2mDBTBPDBq-II), N- (1,1′-biphenyl) is formed over the first light-emitting layer 513. -4-yl) -9,9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl] -9H-fluoren-2-amine (PCBBiF), and bis {2- [ 6- (2,6-Dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} (2,4-pentandionato-κO, O ′) iridium (III) (Ir (ppm-dmp) ₂ (acac) ) Was co-deposited so that the weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (ppm-dmp) ₂ (acac)) was 0.8: 0.2: 0.05 and the film thickness was 20 nm. A second light-emitting layer 514 was formed. Note that in the second light-emitting layer 514, 2mDBTBPDBq-II is the first organic compound (host material), PCBBiF is the second organic compound (assist material), and Ir (ppm-dmp) ₂ (acac) Is a phosphorescent material (guest material).

  On the second light-emitting layer 514, 2mDBTBPDBq-II was sequentially deposited to a thickness of 10 nm and bathophenanthroline (Bphen) to a thickness of 15 nm to form electron transport layers (515 (1) and 515 (2)). On the electron transport layer (515 (1), 515 (2)), lithium fluoride is vapor-deposited to a thickness of 1 nm to form an electron injection layer 516, and aluminum is further adjusted to a thickness of 200 nm. The second electrode 502 was formed by vapor deposition.

Next, the light-emitting element was sealed by fixing the sealing glass substrate on the glass substrate using a sealing material in a glove box in a nitrogen atmosphere. As a sealing method, a sealing material was applied around the light emitting element, and at the time of sealing, ultraviolet light of 365 nm was irradiated at 6 J / cm ² and heat-treated at 80 ° C. for 1 hour. The light emitting element 1 was obtained through the above steps.

<1-2. Production of Light-Emitting Element 2>
Similarly to the light-emitting element 1, DBT3P-II and molybdenum oxide are co-evaporated on the first electrode 501 so that the weight ratio (DBT3P-II: MoO ₃ ) is 2: 1 and the film thickness is 40 nm. Layer 511 was formed.

  PCPPn was deposited on the hole injection layer 511 so as to have a film thickness of 20 nm to form a hole transport layer 512.

  The first light-emitting layer 513 is formed by co-evaporating cgDBCzPA and 1,6mMemFLPAPrn on the hole transport layer 512 so that the weight ratio (cgDBCzPA: 1,6mMemFLPAPrn) is 1: 0.02 and the film thickness is 10 nm. did.

  A separation layer 520 is formed by co-evaporating 2 mDBTBPDBq-II and PCBBiF on the first light-emitting layer 513 so that the weight ratio (2mDBTBPDBq-II: PCBBiF) is 0.6: 0.4 and the film thickness is 2 nm. did.

A weight ratio of 2mDBTBPDBq-II, PCBBiF, and Ir (ppm-dmp) ₂ (acac) over the separation layer 520 (2mDBTBPDBq-II: PCBBiF: Ir (ppm-dmp) ₂ (acac)) is 0.8: 0. The second light-emitting layer 514 was formed by co-evaporation to have a thickness of 2: 0.05 and a thickness of 20 nm.

  On the second light-emitting layer 514, 2mDBTBPDBq-II was sequentially deposited so as to have a thickness of 10 nm and Bphen of 15 nm to form electron transport layers (515 (1) and 515 (2)). On the electron transport layer (515 (1), 515 (2)), lithium fluoride is vapor-deposited to a thickness of 1 nm to form an electron injection layer 516, and aluminum is further adjusted to a thickness of 200 nm. The second electrode 502 was formed by vapor deposition.

  Next, the light-emitting element was sealed by fixing the sealing glass substrate on the glass substrate using a sealing material in a glove box in a nitrogen atmosphere, whereby the light-emitting element 2 was obtained. Note that a sealing method was the same as that of the light-emitting element 1.

<1-3. Production of Light-Emitting Element 3>
The light-emitting element 3 differs from the above-described production of the light-emitting element 1 only in the following steps, and the other steps are the same as those for the light-emitting element 1.

2- [3 ′-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (2mDBTBPDBq-II), N- (1,1′-biphenyl) is formed over the first light-emitting layer 513. -4-yl) -9,9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl] -9H-fluoren-2-amine (PCBBiF), and bis {2- [ 6- (2,6-Dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} (2,4-pentandionato-κO, O ′) iridium (III) (Ir (ppm-dmp) ₂ (acac) ) Was co-deposited so that the weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (ppm-dmp) ₂ (acac)) was 0.5: 0.5: 0.05 and the film thickness was 20 nm. A second light-emitting layer 514 was formed.

<1-4. Production of Light-Emitting Element 4>
The light-emitting element 4 is different from the light-emitting element 2 described above in the following steps, and the other steps are the same as those of the light-emitting element 2 except for the following steps.

On the separation layer 520, 2- [3 ′-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (2mDBTBPDBq-II), N- (1,1′-biphenyl-4-) Yl) -9,9-dimethyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl] -9H-fluoren-2-amine (PCBBiF), and bis {2- [6- ( 2,6-dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} (2,4-pentanedionato-κO, O ′) iridium (III) (Ir (ppm-dmp) ₂ (acac)) The ratio (2mDBTBPDBq-II: PCBiF: Ir (ppm-dmp) ₂ (acac)) is 0.5: 0.5: 0.05 and the film thickness is 20 nm. A light emitting layer 514 was formed.

  Note that, in the above-described vapor deposition process, the vapor deposition was all performed by a resistance heating method.

<1-5. Characteristics of Light-Emitting Element 1 to Light-Emitting Element 4>
FIG. 16A illustrates current density-luminance characteristics of the light-emitting elements 1 to 4. Note that in FIG. 16A, the horizontal axis represents current density (mA / cm ² ) and the vertical axis represents luminance (cd / m ² ). In addition, FIG. 16B illustrates voltage-luminance characteristics of the light-emitting elements 1 to 4. Note that in FIG. 16B, the horizontal axis represents voltage (V) and the vertical axis represents luminance (cd / m ² ). In addition, FIG. 17A illustrates luminance-power efficiency characteristics of the light-emitting elements 1 to 4. Note that in FIG. 17A, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents power efficiency (lm / W). In addition, FIG. 17B illustrates luminance-current efficiency characteristics of the light-emitting elements 1 to 4. Note that in FIG. 17B, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents current efficiency (cd / A). Note that each light-emitting element was measured at room temperature (atmosphere kept at 25 ° C.).

Table 2 shows element characteristics of the light-emitting elements 1 to 4 around 1000 cd / m ² .

Further, FIG. 18 shows an emission spectrum when current is supplied to the light-emitting elements 1 to 4 at a current density of ^2.5 mA / cm ² . As shown in FIG. 18, the light-emitting elements 1 to 4 have peaks observed in the blue and yellow wavelength regions, respectively, indicating that light emission is simultaneously obtained from these two light-emitting materials.

  Note that as shown in Table 1, the light-emitting element 1 and the light-emitting element 2 are different in the presence or absence of the separation layer 520. Further, the light emitting element 3 and the light emitting element 4 are different in the presence or absence of the separation layer 520. From the results shown in FIGS. 16 and 17, the light-emitting element 1 and the light-emitting element 2 have substantially the same element characteristics regardless of the presence or absence of the separation layer 520. From the results shown in FIGS. 16 and 17, the light emitting element 3 and the light emitting element 4 have substantially the same element characteristics regardless of the presence or absence of the separation layer 520. Note that when the light-emitting element 1 and the light-emitting element 2 are compared with the light-emitting element 3 and the light-emitting element 4, the second organic compound (assist material) of the second light-emitting layer 514 of the light-emitting element 3 and the light-emitting element 4 is used. The concentration of PCBBiF is increased. Thereby, it turns out that the yellow spectrum intensity | strength is high. Therefore, it was found that the device characteristics of high efficiency are maintained and the yellow spectral intensity is easily adjusted. From the results shown in FIG. 18, it was confirmed that in the light-emitting element 1 and the light-emitting element 2, the intensity ratio of the blue and yellow emission spectra can be adjusted by the presence or absence of the separation layer 520.

  As described above, the structure described in this example can be combined with any of the other examples and embodiments as appropriate.

  In this example, an example of manufacturing a light-emitting element which is one embodiment of the present invention will be described. FIG. 15B is a schematic cross-sectional view of the light-emitting element (light-emitting element 5) manufactured in this example, Table 3 shows details of the element structure, and structures and abbreviations of the compounds used are shown below. Note that the structures and names of the compounds used in the light-emitting elements 1 to 4 described in Example 1 are omitted.

<2-1. Production of Light-Emitting Element 5>
Similarly to the light-emitting element 1, DBT3P-II and molybdenum oxide are co-evaporated on the first electrode 501 so that the weight ratio (DBT3P-II: MoO ₃ ) is 2: 1 and the film thickness is 20 nm, and hole injection is performed. Layer 511 was formed.

  PCPPn was deposited on the hole injection layer 511 so as to have a film thickness of 20 nm to form a hole transport layer 512.

  On the hole transport layer 512, cgDBCzPA and N, N′-bis (dibenzofuran-4-yl) -N, N′-diphenyl-pyrene-1,6-diamine (1,6FrAPrn-II) were weight ratio (cgDBCzPA). : 1,6FrAPrn-II) was 1: 0.03, and the first light-emitting layer 513 was formed by co-evaporation so that the film thickness was 5 nm. Note that in the first light-emitting layer 513, cgDBCzPA is a host material, and 1,6FrAPrn-II is a fluorescent material (guest material).

  A separation layer 520 is formed by co-evaporating 2 mDBTBPDBq-II and PCBBiF on the first light-emitting layer 513 so that the weight ratio (2mDBTBPDBq-II: PCBBiF) is 0.6: 0.4 and the film thickness is 2 nm. did.

On the separation layer 520, 2mDBTBPDBq-II, PCBBiF, and bis {4,6-dimethyl-2- [6- (2,6-dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} (2,4-pentane dionato -κ ² O, O ') iridium _{(III) (Ir (dmppm-} dmp) 2 (acac)) the weight ratio (2mDBTBPDBq-II: PCBBiF: Ir (dmppm-dmp) 2 (acac)) is zero. The second light-emitting layer 514 was formed by co-evaporation so that the film thickness was 8: 0.2: 0.05 and 20 nm. Note that in the second light-emitting layer 514, 2mDBTBPDBq-II is the first organic compound (host material), PCBBiF is the second organic compound (assist material), and Ir (dmppm-dmp) ₂ (acac) Is a phosphorescent material (guest material).

  On the second light-emitting layer 514, 2mDBTBPDBq-II was sequentially deposited so as to have a thickness of 10 nm and Bphen of 15 nm to form electron transport layers (515 (1) and 515 (2)). On the electron transport layer (515 (1), 515 (2)), lithium fluoride is vapor-deposited to a thickness of 1 nm to form an electron injection layer 516, and aluminum is further adjusted to a thickness of 200 nm. The second electrode 502 was formed by vapor deposition.

  Note that, in the above-described vapor deposition process, the vapor deposition was all performed by a resistance heating method.

  Next, the light emitting element was sealed by fixing the sealing glass substrate on the glass substrate using a sealing material in a glove box in a nitrogen atmosphere, whereby the light emitting element 5 was obtained. Note that a sealing method was the same as that of the light-emitting element 1.

<2-2. Characteristics of Light-Emitting Element 5>
A current density-luminance characteristic of the light-emitting element 5 is illustrated in FIG. Note that in FIG. 19A, the horizontal axis represents current density (mA / cm ² ) and the vertical axis represents luminance (cd / m ² ). Further, voltage-luminance characteristics of the light-emitting element 5 are illustrated in FIG. Note that in FIG. 19B, the horizontal axis represents voltage (V) and the vertical axis represents luminance (cd / m ² ). In addition, FIG. 20A illustrates luminance-power efficiency characteristics of the light-emitting element 5. In FIG. 20A, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents power efficiency (lm / W). In addition, FIG. 20B illustrates luminance-current efficiency characteristics of the light-emitting element 5. Note that in FIG. 20B, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents current efficiency (cd / A). Note that the measurement of the light-emitting element was performed at room temperature (atmosphere kept at 25 ° C.).

Table 4 shows element characteristics of the light-emitting element 5 around 1000 cd / m ² .

FIG. 21 shows an emission spectrum obtained when a current is passed through the light-emitting element 5 at a current density of ^2.5 mA / cm ² . As shown in FIG. 21, since the light emitting element 5 has peaks observed in the blue and yellow wavelength regions, it can be seen that light emission is simultaneously obtained from these two light emitting materials.

The light-emitting element 5 of this example is different from the light-emitting elements 1 to 4 shown in Example 1 in the fluorescent material of the first light-emitting layer 513 and the phosphorescent material of the second light-emitting layer 514. From the results shown in FIGS. 19 and 20, it is understood that the light-emitting element 5 has high-efficiency element characteristics like the light-emitting elements 1 to 4 shown in Example 1. The correlated color temperature of the light-emitting element 5 around 1000 cd / m ² was measured and found to be 2850K. Therefore, it turns out that it can be used also as an illumination use.

  As described above, the structure described in this example can be combined with any of the other examples and embodiments as appropriate.

  In this example, an example of manufacturing a light-emitting element which is one embodiment of the present invention will be described. FIG. 15B is a schematic cross-sectional view of a light-emitting element (light-emitting element 6) manufactured in this example, Table 5 shows details of the element structure, and structures and abbreviations of the compounds used are shown below. Note that the structures and names of the compounds used in the light-emitting elements 1 to 4 described in Example 1 are omitted.

<3-1. Production of Light-Emitting Element 6>
Similarly to the light-emitting element 1, DBT3P-II and molybdenum oxide are co-evaporated on the first electrode 501 so that the weight ratio (DBT3P-II: MoO ₃ ) is 2: 1 and the film thickness is 20 nm, and hole injection is performed. Layer 511 was formed.

  PCPPn was deposited on the hole injection layer 511 so as to have a film thickness of 20 nm to form a hole transport layer 512.

  The first light-emitting layer 513 is formed by co-evaporating cgDBCzPA and 1,6mMemFLPAPrn on the hole transport layer 512 so that the weight ratio (cgDBCzPA: 1,6mMemFLPAPrn) is 1: 0.03 and the film thickness is 5 nm. did.

  A separation layer 520 is formed by co-evaporating 2 mDBTBPDBq-II and PCBBiF on the first light-emitting layer 513 so that the weight ratio (2mDBTBPDBq-II: PCBBiF) is 0.6: 0.4 and the film thickness is 2 nm. did.

2mDBTBPDBq-II, PCBBiF, and (acetylacetonato) bis [5-methyl-6- (2-methylphenyl) -4-phenylpyrimidinato] iridium (III) (also known as bis {2- [5-Methyl-6- (2-methylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} (2,4-pentanedionato-κ ² O, O ′) iridium (III)) (Ir (mpmppm) ₂ (acac)) was co-deposited so that the weight ratio (2mDBTBPDBq-II: PCBiF: Ir (mpmppm) ₂ (acac)) was 0.8: 0.2: 0.05 and the film thickness was 20 nm. Two light emitting layers 514 were formed. Note that in the second light-emitting layer 514, 2mDBTBPDBq-II is the first organic compound (host material), PCBBiF is the second organic compound (assist material), and Ir (mpmppm) ₂ (acac) is phosphorescent. It is a material (guest material).

  On the second light-emitting layer 514, 2mDBTBPDBq-II was sequentially deposited so as to have a thickness of 10 nm and Bphen of 15 nm to form electron transport layers (515 (1) and 515 (2)). On the electron transport layer (515 (1), 515 (2)), lithium fluoride is vapor-deposited to a thickness of 1 nm to form an electron injection layer 516, and aluminum is further adjusted to a thickness of 200 nm. The second electrode 502 was formed by vapor deposition.

  Note that, in the above-described vapor deposition process, the vapor deposition was all performed by a resistance heating method.

  Next, the light emitting element was sealed by fixing the sealing glass substrate on the glass substrate using a sealing material in a glove box in a nitrogen atmosphere, whereby the light emitting element 6 was obtained. Note that a sealing method was the same as that of the light-emitting element 1.

<3-2. Characteristics of Light-Emitting Element 6>
FIG. 22A shows current density-luminance characteristics of the light-emitting element 6. Note that in FIG. 22A, the horizontal axis represents current density (mA / cm ² ) and the vertical axis represents luminance (cd / m ² ). Further, voltage-luminance characteristics of the light-emitting element 6 are illustrated in FIG. Note that in FIG. 22B, the horizontal axis represents voltage (V) and the vertical axis represents luminance (cd / m ² ). In addition, FIG. 23A illustrates luminance-power efficiency characteristics of the light-emitting element 6. Note that in FIG. 23A, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents power efficiency (lm / W). In addition, FIG. 23B illustrates luminance-current efficiency of the light-emitting element 6. Note that in FIG. 23B, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents current efficiency (cd / A). Note that the measurement of the light-emitting element was performed at room temperature (atmosphere kept at 25 ° C.).

Table 6 shows element characteristics of the light-emitting element 6 around 1000 cd / m ² .

Further, FIG. 24 shows an emission spectrum obtained when a current is passed through the light-emitting element 6 at a current density of ^2.5 mA / cm ² . As shown in FIG. 24, since the light emitting element 6 has peaks observed in the blue and yellow wavelength regions, it can be seen that light emission is simultaneously obtained from these two light emitting materials.

The light-emitting element 6 of this example is different from the light-emitting elements 1 to 4 shown in Example 1 in the phosphorescent material of the second light-emitting layer 514. From the results shown in FIGS. 22 and 23, it is understood that the light-emitting element 6 has high-efficiency element characteristics, similar to the light-emitting elements 1 to 4 shown in Example 1. In addition, the correlated color temperature of the light-emitting element 6 around 1000 cd / m ² was measured and found to be 3090K. Therefore, it turns out that it can be used also as an illumination use.

  As described above, the structure described in this example can be combined with any of the other examples and embodiments as appropriate.

  In this example, an example of manufacturing a light-emitting element which is one embodiment of the present invention will be described. FIG. 25 shows a schematic cross-sectional view of the light-emitting elements (light-emitting elements 7 to 10) manufactured in this example, and Table 7 shows details of the element structure. Note that. Since the structures of the compounds used for the light-emitting elements 7 to 10 are the same as the structures of the compounds used for the light-emitting elements 1 to 6, description thereof is omitted here.

<4-1. Production of Light-Emitting Element 7 to Light-Emitting Element 10>
A 200-nm film of an alloy film (Al—Ni—La) of aluminum (Al), nickel (Ni), and lanthanum (La) is formed as a first electrode 501 (1) over a glass substrate 500 by a sputtering method. A film was formed with a thickness. Next, as the first electrode 501 (2), titanium (Ti) was formed to a thickness of 6 nm by a sputtering method, and a heat treatment was performed at 300 ° C. for 1 hour, so that a film containing titanium oxide was formed. Next, indium tin oxide containing silicon oxide (ITSO) was formed as the first electrode 501 (3) by a sputtering method. Note that the first electrode 501 (1), the first electrode 501 (2), and the first electrode 501 (3) form the first electrode 501 and the electrode area of the first electrode 501 is 2 mm. X2 mm.

  The thickness of the first electrode 501 (3) of the light-emitting element 7, the light-emitting element 8, and the light-emitting element 10 was 75 nm, and the thickness of the first electrode 501 (3) of the light-emitting element 9 was 40 nm.

Next, DBT3P-II and molybdenum oxide were co-evaporated on the first electrode 501 (3) so that the weight ratio (DBT3P-II: MoO ₃ ) was 2: 1, whereby a hole injection layer 511 was formed. .

  In addition, the thickness of the hole injection layer 511 of the light emitting element 7 is 87.5 nm, the thickness of the hole injection layer 511 of the light emitting element 8 is 57.5 nm, and the thickness of the hole injection layer 511 of the light emitting element 9. Is 50 nm, and the thickness of the hole injection layer 511 of the light-emitting element 10 is 65 nm.

  Next, PCPPn was deposited on the hole injection layer 511 so as to have a film thickness of 20 nm to form a hole transport layer 512.

  The first light-emitting layer 513 is formed by co-evaporating cgDBCzPA and 1,6mMemFLPAPrn on the hole transport layer 512 so that the weight ratio (cgDBCzPA: 1,6mMemFLPAPrn) is 1: 0.02 and the film thickness is 10 nm. did.

  A separation layer 520 is formed by co-evaporating 2 mDBTBPDBq-II and PCBBiF on the first light-emitting layer 513 so that the weight ratio (2mDBTBPDBq-II: PCBBiF) is 0.2: 0.3 and the film thickness is 2 nm. did.

A weight ratio of 2mDBTBPDBq-II, PCBBiF, and Ir (mpmppm) ₂ (acac) to the separation layer 520 (2mDBTBPDBq-II: PCBBiF: Ir (mpmppm) ₂ (acac) is 0.8: 0.2: 0.06. The second light-emitting layer 514 was formed by co-evaporation so that the film thickness was 20 nm.

  2mDBTBPDBq-II and Bphen were sequentially deposited on the second light-emitting layer 514 so that the film thicknesses were 15 nm and 20 nm, respectively, to form electron transport layers (515 (1) and 515 (2)). Lithium fluoride was deposited on the electron transport layer (515 (1), 515 (2)) to a thickness of 1 nm to form an electron injection layer 516.

  A second electrode is formed by co-evaporating an alloy of silver (Ag) and magnesium (Mg) on the electron injection layer 516 so that the volume ratio (Ag: Mg) is 0.5: 0.05 and the film thickness is 15 nm. 502 (1) was formed.

  Next, an ITO film was formed over the second electrode 502 (1) by a sputtering method so as to have a thickness of 70 nm.

  As shown in Table 7, the sealing substrate 550 of the light-emitting element 7 has a red (R) color filter with a thickness of 2.36 μm as the colored layer 552, and the sealing substrate 550 of the light-emitting element 8 has The colored layer 552 is a green (G) color filter with a thickness of 1.29 μm, and the sealing substrate 550 of the light-emitting element 9 is a colored layer 552 with a blue (B) color filter having a thickness of 0.78 μm. A yellow (Y) color filter having a thickness of 0.80 μm was formed as the colored layer 552 on the sealing substrate 550 of the light emitting element 10.

The light-emitting elements 7 to 10 manufactured as described above and the sealing substrate manufactured as described above were sealed in a glove box in a nitrogen atmosphere so as not to be exposed to the atmosphere. This was applied, and irradiated with 6 J / cm ² of 365 nm ultraviolet light at the time of sealing, and heat-treated at 80 ° C. for 1 hour).

  Note that, in the above-described vapor deposition process, the vapor deposition was all performed by a resistance heating method.

<4-2. Characteristics of Light-Emitting Element 7 to Light-Emitting Element 10>
A current density-luminance characteristic of the light-emitting elements 7 to 10 is illustrated in FIG. Note that in FIG. 26A, the horizontal axis represents current density (mA / cm ² ) and the vertical axis represents luminance (cd / m ² ). In addition, FIG. 26B illustrates voltage-luminance characteristics of the light-emitting elements 7 to 10. Note that in FIG. 26B, the horizontal axis represents voltage (V) and the vertical axis represents luminance (cd / m ² ). Note that each light-emitting element was measured at room temperature (atmosphere kept at 25 ° C.).

Table 8 shows element characteristics of the light-emitting elements 7 to 10 around 1000 cd / m ² .

In addition, FIG. 27 shows an emission spectrum when current is supplied to the light-emitting elements 7 to 10 at a current density of ^2.5 mA / cm ² . As shown in FIG. 27, the light emitting element 7 has a peak observed in the red wavelength region, the light emitting element 8 has a peak observed in the green wavelength region, and the light emitting element 9 has a peak observed in the blue wavelength region. A peak of 10 is observed in the yellow wavelength region. Therefore, it can be seen that full color can be realized by using the light emitting elements 7 to 10 in combination.

  The light-emitting elements 7 to 10 manufactured in this example use the same first light-emitting layer 513 and second light-emitting layer 514 as shown in Table 7. From the results shown in FIGS. 26 and 27, even when the first light-emitting layer 513 and the second light-emitting layer 514 have the same structure, the light-emitting elements having different emission spectra have high current efficiency and are excellent. It was confirmed that the device characteristics were satisfactory.

  As described above, the structure described in this example can be combined with any of the other examples and embodiments as appropriate.

(Reference example)
The synthesis method of Ir (ppm-dmp) ₂ (acac) used in Example 1 and Example 2 will be described. The synthesis scheme is as follows.

<Synthesis of 1.4-chloro-6-phenylpyrimidine>
4,6-dichloropyrimidine 5.0 g, phenylboronic acid 4.9 g, sodium carbonate 7.1 g, bis (triphenylphosphine) palladium (II) dichloride (Pd (PPh ₃ ) ₂ Cl ₂ ) 0.34 g, acetonitrile 20 mL The mixture of 20 mL of water was heated to reflux by irradiation with microwaves (2.45 GHz, 100 W) for 1 hour under an argon stream. The obtained mixture was extracted with dichloromethane and purified by silica gel column chromatography (developing solvent: dichloromethane) to obtain 1.6 g of 4-chloro-6-phenylpyrimidine (yield: 23%, pale yellow solid). Got in. In this reference example, microwave irradiation was performed using a microwave synthesizer (Discover manufactured by CEM).

<Synthesis of 2.4-phenyl-6- (2,6-dimethylphenyl) pyrimidine (Hppm-dmp)>
4-chloro-6-phenylpyrimidine 1.6 g, 2,6-dimethylphenylboronic acid 1.5 g, sodium carbonate 1.8 g, Pd (PPh ₃ ) ₂ Cl ₂ 59 mg, N, N-dimethylformamide 20 mL, water 20 mL The mixture was heated and refluxed by irradiation with microwaves (2.45 GHz, 100 W) for 2 hours under an argon stream. The resulting mixture was extracted with dichloromethane and purified by silica gel column chromatography (developing solvent: ethyl acetate: hexane = 1: 5) to obtain 0.50 g of Hppm-dmp (yield: 23%, pale yellow Oil).

<3. Di-μ-chloro-tetrakis {2- [6- (2,6-dimethylphenyl) -4-pyrimidinyl-κN3] phenyl-κC} diiridium (III) ([Ir (ppm-dmp) ₂ Cl] ₂ ) Synthesis>
By irradiating a mixture of Hppm-dmp 1.0 g, iridium (III) chloride hydrate 0.57 g, 2-ethoxyethanol 20 mL, and water 20 mL with microwaves (2.45 GHz 100 W) for 3 hours under an argon stream. Heated to reflux. The obtained mixture was filtered, and the solid was washed with methanol to obtain 1.1 g of [Ir (ppm-dmp) ₂ Cl] ₂ (yield: 74%, orange solid).

<4. Synthesis of Ir (ppm-dmp) ₂ (acac)>
A mixture of 1.1 g of [Ir (ppm-dmp) ₂ Cl] ₂ , 0.77 g of sodium carbonate, 0.23 g of acetylacetone (Hacac), and 30 mL of 2-ethoxyethanol was subjected to microwave (2.45 GHz 120 W under an argon stream. ) Was heated to reflux by irradiation for 2 hours. The obtained mixture was filtered, and the insoluble part was washed with methanol. The obtained filtrate was concentrated, the residue was purified by silica gel column chromatography (developing solvent: ethyl acetate: hexane = 1: 5), and the obtained solid was recrystallized from hexane to give Ir (ppm-dmp ) ₂ (acac) was obtained (yield: 59%, orange powder solid). 0.21 g of the obtained orange powder solid was purified by sublimation by a train sublimation method, and the target orange solid was recovered at a yield of 48%. The sublimation purification conditions were a pressure of 2.7 Pa, an argon gas flow rate of 5.0 mL / min, and 240 ° C. ¹ H-NMR (nuclear magnetic resonance) spectrum data of the obtained Ir (ppm-dmp) ₂ (acac) is shown below.

¹ H-NMR. δ (CDCl ₃ ): 1.85 (s, 6H), 2.26 (s, 12H), 5.35 (s, 1H), 6.46-6.48 (dd, 2H), 6.83- 6.90 (dm, 4H), 7.20-7.22 (d, 4H), 7.29-7.32 (t, 2H), 7.63-7.65 (dd, 2H), 7. 72 (ds, 2H), 9.24 (ds, 2H).

  In this example, the light-emitting element 11 having only the first light-emitting layer in the structure of the light-emitting element which is one embodiment of the present invention and the second light-emitting layer in the structure of the light-emitting element which is one embodiment of the present invention are included. An example of manufacturing the light-emitting element 12 will be described. In addition, the compound (N, N ′-(pyrene-1,6-diyl) bis [(6, N-diphenylbenzo [b] naphtho [1,2-d] furan) -8-amine used in this example) ] (Abbreviation: 1,6BnfAPrn-03)) is shown below. Note that the structures and names of the compounds used in the light-emitting elements described in the other examples are omitted.

<5-1. Production of Light-Emitting Elements 11 and 12>
The light-emitting element 11 has a structure in which a hole injection layer 511, a hole transport layer 512, and a first light-emitting layer 513 are stacked over the first electrode 501, similarly to the light-emitting element 1 described in Embodiment 1. In this structure, the electron-transporting layers 515 (1) and 515 (2), the electron-injecting layer 516, and the second electrode 502 are sequentially stacked on the first light-emitting layer 513 without forming the second light-emitting layer 514. is there. The light-emitting element 12 has a structure in which a hole injection layer 511 and a hole transport layer 512 are stacked over the first electrode 501 similarly to the light-emitting element 1 described in Example 1, but the first light-emitting element 12 has A structure in which the second light-emitting layer 514, the electron transport layers 515 (1) and 515 (2), the electron injection layer 516, and the second electrode 502 are sequentially stacked over the hole transport layer 512 without forming the layer 513. It is.

Therefore, Example 1 is referred to for a specific method for manufacturing the light-emitting element, and the detailed element structure of the light-emitting elements (light-emitting elements 11 and 12) manufactured in this example is as shown in Table 9. .

<5-2. Characteristics of Light-Emitting Elements 11 and 12>
The luminance-external quantum efficiency characteristic of the light-emitting element 11 is shown in FIG. 28, and the luminance-external quantum efficiency characteristic of the light-emitting element 12 is shown in FIG. 28 and 31, the horizontal axis represents luminance (cd / m ² ) and the vertical axis represents external quantum efficiency (%). Note that the measurement of the light-emitting element was performed at room temperature (atmosphere kept at 25 ° C.).

Table 10 shows element characteristics of the light-emitting elements 11 and 12 around 1000 cd / m ² .

In addition, FIG. 29 shows an emission spectrum when current is passed through the light-emitting element 11 at a current density of ^2.5 mA / cm ² . Similarly, FIG. 32 shows an emission spectrum when current is passed through the light-emitting element 12 at a current density of ^2.5 mA / cm ² . 29 and 32, the horizontal axis represents wavelength (nm) and the vertical axis represents emission intensity (arbitrary unit). As shown in FIG. 29, since the light emitting element 11 has a peak in the blue wavelength region, it can be seen that light emission from the light emitting material included in the first light emitting layer 513 is obtained. In addition, as shown in FIG. 32, the light-emitting element 12 has a peak in the yellow wavelength region, which indicates that light emission from the light-emitting material included in the second light-emitting layer 514 is obtained.

In addition, a reliability test was performed on the light-emitting element 11 and the light-emitting element 12. FIG. 30 shows the results measured for the light-emitting element 11, and FIG. 33 shows the results measured for the light-emitting element 12. 30 and 33, the vertical axis represents normalized luminance (%) when the initial luminance is 100%, and the horizontal axis represents element driving time (h). Note that in the reliability test, the initial luminance was set to 5000 cd / m ² , and the light-emitting element 11 and the light-emitting element 12 were driven under conditions of constant current density. As a result, it was possible to maintain approximately 90% of the initial luminance of each of the light emitting elements 11 up to 130 hours and the light emitting elements 12 up to 1300 hours.

  As described above, the structure described in this example can be combined with any of the other examples and embodiments as appropriate.

(Reference example)
In this reference example, the organic compound used in the examples, N, N ′-(pyrene-1,6-diyl) bis [(6, N-diphenylbenzo [b] naphtho [1,2-d] furan) − 8-amine] (abbreviation: 1,6BnfAPrn-03) will be described. The structure of 1,6BnfAPrn-03 is shown below.

<Step 1: Synthesis of 6-iodobenzo [b] naphtho [1,2-d] furan>
To a 500 mL three-necked flask, 8.5 g (39 mmol) of benzo [b] naphtho [1,2-d] furan was added, the inside of the flask was purged with nitrogen, and 195 mL of tetrahydrofuran (THF) was added. The solution was cooled to −75 ° C., and 25 mL (40 mmol) of n-butyllithium (1.59 mol / L n-hexane solution) was added dropwise to the solution. After the dropwise addition, the resulting solution was stirred at room temperature for 1 hour.

  After a predetermined time, this solution was cooled to −75 ° C., and then a solution of iodine 10 g (40 mmol) dissolved in THF 40 mL was added dropwise. After dropping, the resulting solution was stirred for 17 hours while returning to room temperature. After a predetermined time, an aqueous sodium thiosulfate solution was added to the mixture and stirred for 1 hour. The organic layer of the mixture was washed with water, and the organic layer was dried over magnesium sulfate. After drying, the mixture was naturally filtered, and the resulting solution was sucked through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-1855) and Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 540-00135). Filtered. The solid obtained by concentrating the obtained filtrate was recrystallized with toluene, and the target white powder was obtained in a yield of 6.0 g (18 mmol) and a yield of 45%. The synthesis scheme of Step 1 is shown below.

<Step 2:. Synthesis of 6-phenylbenzo [b] naphtho [1,2-d] furan>
In a 200 mL three-necked flask, 6.0 g (18 mmol) 6-iodobenzo [b] naphtho [1,2-d] furan, 2.4 g (19 mmol) phenylboronic acid, 70 mL toluene, 20 mL ethanol, 22 mL of an aqueous potassium carbonate solution (2.0 mol / L) was added. This mixture was deaerated by stirring it under reduced pressure. After degassing, the flask was under nitrogen, and 480 mg (0.42 mmol) of tetrakis (triphenylphosphine) palladium (0) was added. This mixture was stirred at 90 ° C. for 12 hours under a nitrogen stream.

  After a predetermined time, water was added to the mixture to separate the organic layer and the aqueous layer. The extract extracted from the aqueous layer with toluene and the organic layer were combined, washed with water, and dried over magnesium sulfate. The mixture was naturally filtered, and the resulting filtrate was concentrated to dissolve the solid obtained in toluene. The obtained solution was suction filtered through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855), Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 540-00135), and alumina. The solid obtained by concentrating the obtained filtrate was recrystallized with toluene, and the target white solid was obtained in a yield of 4.9 g (17 mmol) and a yield of 93%. The synthesis scheme of Step 2 is shown below.

<Step 3: Synthesis of 8-iodo-6-phenylbenzo [b] naphtho [1,2-d] furan>
To a 300 mL three-necked flask, 4.9 g (17 mmol) of 6-phenylbenzo [b] naphtho [1,2-d] was added, the inside of the flask was purged with nitrogen, and 87 mL of tetrahydrofuran (THF) was added. The solution was cooled to −75 ° C., and 11 mL (18 mmol) of n-butyllithium (1.59 mol / L n-hexane solution) was added dropwise to the solution. After the dropwise addition, the resulting solution was stirred at room temperature for 1 hour. After a predetermined time, this solution was cooled to −75 ° C., and a solution obtained by dissolving 4.6 g (18 mmol) of iodine in 18 mL of THF was added dropwise.

  The resulting solution was stirred for 17 hours while returning to room temperature. After a predetermined time, an aqueous sodium thiosulfate solution was added to the mixture and stirred for 1 hour. The organic layer of the mixture was washed with water, and the organic layer was dried over magnesium sulfate. The filtrate obtained by natural filtration of this mixture was filtered by suction through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855), Florisil (Wako Pure Chemical Industries, Ltd., catalog number: 540-00135), and alumina. did. The solid obtained by concentrating the obtained filtrate was recrystallized with toluene, and the target white solid was obtained in a yield of 3.7 g (8.8 mmol) and a yield of 53%. The synthesis scheme of Step 3 is shown below.

<Step 4: Synthesis of 1,6BnfAPrn-03>
In a 100 mL three-necked flask, 0.71 g (2.0 mmol) 1,6-dibromopyrene, 1.0 g (10.4 mmol) sodium tert-butoxide, 10 mL toluene, 0.36 mL (4.0 mmol) Aniline and 0.3 mL of tri (tert-butyl) phosphine in 10 wt% hexane were added, and the atmosphere in the flask was replaced with nitrogen. 50 mg (85 μmol) of bis (dibenzylideneacetone) palladium (0) was added to this mixture, and the mixture was stirred at 80 ° C. for 2 hours.

  After a predetermined time, 1.7 g (4.0 mmol) of 8-iodo-6-phenylbenzo [b] naphtho [1,2-d] furan and 180 mg (0.44 mmol) of 2 were added to the resulting mixture. -Dicyclohexylphosphino-2 ′, 6′-dimethoxybiphenyl (abbreviation: S-Phos) and 50 mg (85 μmol) of bis (dibenzylideneacetone) palladium (0) were added and the mixture was stirred at 100 ° C. for 15 hours. . After a predetermined time elapsed, the obtained mixture was filtered through Celite (Wako Pure Chemical Industries, Ltd., catalog number: 531-16855). The solid obtained by concentrating the obtained filtrate was washed with ethanol and recrystallized with toluene. As a result, 1.38 g (1.4 mmol) of the target yellow solid was obtained in a yield of 71%.

  Sublimation purification of 1.37 mg (1.4 mmol) of the obtained yellow solid was performed by a train sublimation method. The sublimation purification was performed by heating the yellow solid at 370 ° C. under the conditions of an argon flow rate of 10 mL / min and a pressure of 2.3 Pa. After purification by sublimation, 0.68 g (0.70 mmol) of a yellow solid was obtained with a recovery rate of 50%. The synthesis scheme of Step 4 is shown below.

Incidentally, showing nuclear magnetic resonance spectroscopy of the yellow solid obtained in Step 4 the analysis result by ^{(1 H} NMR) as follows. From this result, it was found that 1,6BnfAPrn-03 was obtained.

¹ H NMR (dichloromethane-d2, 500 MHz): δ = 6.88 (t, J = 7.7 Hz, 4H), 7.03-7.06 (m, 6H), 7.11 (t, J = 7) 0.5 Hz, 2H), 7.13 (d, J = 8.0 Hz, 2H), 7.28-7.32 (m, 8H), 7.37 (t, J = 8.0 Hz, 2H), 7 .59 (t, J = 7.2 Hz, 2H), 7.75 (t, J = 7.7 Hz, 2H), 7.84 (d, J = 9.0 Hz, 2H), 7.88 (d, J = 8.0 Hz, 2H), 8.01 (s, 2H), 8.07 (d, J = 8.0 Hz, 4H), 8.14 (d, J = 9.0 Hz, 2H), 8. 21 (d, J = 8.0 Hz, 2H), 8.69 (d, J = 8.5 Hz, 2H).

DESCRIPTION OF SYMBOLS 100 Light emitting element 101 Electrode 102 Electrode 111 Hole injection layer 112 Hole transport layer 113 Light emitting layer 114 Light emitting layer 115 Electron transport layer 116 Electron injection layer 120 Separation layer 130 EL layer 131 Light emitting unit 132 Light emitting unit 133 Charge generation layer 140 Light emitting element 150 light emitting element 160 light emitting element 170 light emitting element 500 glass substrate 501 electrode 502 electrode 511 hole injection layer 512 hole transport layer 513 light emission layer 514 light emission layer 515 (1) electron transport layer 515 (2) electron transport layer 516 electron injection layer 520 Separation layer 550 Sealing substrate 552 Colored layer 600 Light-emitting device 601 Source line driver circuit portion 602 Pixel portion 603 Gate line driver circuit portion 604 Sealing substrate 605 Sealant 607 Region 608 Wiring 609 FPC
610 Element substrate 611 FET
612 FET
613 Electrode 614 Insulator 616 EL layer 617 Electrode 618 Light emitting element 623 FET
624 FET
801 Pixel circuit 802 Pixel portion 804 Drive circuit portion 804a Gate driver 804b Source driver 806 Protection circuit 807 Terminal portion 852 Transistor 854 Transistor 862 Capacitance element 872 Light emitting element 1001 Substrate 1002 Base insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 Gate Electrode 1020 Interlayer insulating film 1021 Interlayer insulating film 1022 Electrode 1024B Electrode 1024G Electrode 1024R Electrode 1024Y Electrode 1025 Partition 1026 Electrode 1028 EL layer 1031 Sealing substrate 1032 Sealing material 1033 Base material 1034B Colored layer 1034G Colored layer 1034R Colored layer 1034Y Colored layer 1035 Black Layer 1036 Overcoat layer 1037 Interlayer insulating film 1040 Pixel portion 1041 Drive circuit portion 1042 Peripheral portion 8000 Display module 8001 Upper cover 8002 Lower cover 8003 FPC
8004 Touch panel 8005 FPC
8006 Display panel 8009 Frame 8010 Printed circuit board 8011 Battery 8501 Lighting device 8502 Lighting device 8503 Lighting device 8504 Lighting device 9000 Case 9001 Display unit 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9050 Operation button 9051 Information 9052 Information 9053 Information 9054 Information 9055 hinge 9100 portable information terminal 9101 portable information terminal 9102 portable information terminal 9200 portable information terminal 9201 portable information terminal

Claims (15)

A light-emitting element in which an EL layer is sandwiched between a pair of electrodes,
The EL layer is
A first light emitting layer;
A second light emitting layer,
The first light emitting layer includes
A fluorescent material;
A host material,
The second light emitting layer includes
A phosphorescent material, a first organic compound, and a second organic compound,
The emission spectrum from the second light emitting layer is:
It has a peak in the yellow wavelength region,
The first organic compound and the second organic compound form an exciplex,
A light emitting element characterized by the above. In claim 1,
The phosphorescent material is one,
A light emitting element characterized by the above. In claim 1,
There is energy transfer from the exciplex to the phosphorescent material,
A light emitting element characterized by the above. In claim 1,
The singlet excitation level of the host material is
Greater than the singlet excitation level of the fluorescent material;
The triplet excited level of the host material is
Smaller than the triplet excitation level of the fluorescent material,
A light emitting element characterized by the above. In claim 1 or claim 4,
The triplet excited level of the host material is
Smaller than the triplet excited level of the first organic compound and the second organic compound,
A light emitting element characterized by the above. In claim 1,
The first light-emitting layer and the second light-emitting layer have a region in contact with each other;
A light emitting element characterized by the above. In claim 1,
The first light-emitting layer and the second light-emitting layer have regions separated from each other;
A light emitting element characterized by the above. In claim 7,
Between the first light emitting layer and the second light emitting layer,
Having a layer in which a hole transporting material and an electron transporting material are mixed;
A light emitting element characterized by the above. In claim 1 or any one of claims 6 to 8,
The second light emitting layer is provided on the first light emitting layer.
A light emitting element characterized by the above. A light emitting device according to any one of claims 1 to 9,
Having a transistor or substrate,
A light emitting device characterized by that. A light emitting device according to claim 10;
A connector connected to the light emitting device,
A module characterized by that. In claim 11,
The connector is
FPC or TCP,
A module characterized by that. A light emitting device according to claim 10;
An external connection port, a keyboard, operation buttons, a speaker, or a microphone;
An electronic device characterized by that. A module according to claim 11 or claim 12,
An external connection port, a keyboard, operation buttons, a speaker, or a microphone;
An electronic device characterized by that. A light emitting device according to claim 10;
Having a housing,
A lighting device characterized by that.